This PR adds some basic stories for collab notifications to make them
easier to work on:

<img width="1076" alt="Screenshot 2024-01-08 at 9 43 39 PM"
src="https://github.com/zed-industries/zed/assets/1486634/4a0adcfa-1134-49c2-b589-74ac1d52af4c">

I factored out a `CollabNotification` component that defines the general
structure for one of these notifications, and this is the component that
we use in the stories, with representative values passed to it to
simulate the different instances of the notification.

We can't use the actual notification components in the stories due to
their data dependencies.

Release Notes:

- N/A

This PR fixes an issue where right-click on any project panel entry
would cause the context menu on the root of the project panel
(introduced in #3954) to deploy.

We need to stop propagation in the handler on the inner project panel
list items so that the click event doesn't bubble up the tree.

Release Notes:

- Fixed an issue where the project panel was always deploying the root
context menu rather than on the clicked item.

Fixes https://github.com/zed-industries/community/issues/2379

Release Notes:

- Fixed issue where keybindings in some context menus would not show
reliably.

As it says on the tin

Release Notes:

- Restored the terminal cursor's I-beam and pointing hand settings

As it says on the tin

Release Notes:

- Restored the active pane magnification setting.

Release Notes:

- N/A

This PR tightens up the design of the feedback dialog:

<img width="680" alt="Screenshot 2024-01-08 at 6 20 50 PM"
src="https://github.com/zed-industries/zed/assets/1486634/8dc0e687-2459-4ab3-b69f-b610ce067ef1">

<img width="682" alt="Screenshot 2024-01-08 at 6 21 24 PM"
src="https://github.com/zed-industries/zed/assets/1486634/f0730710-16e0-4d61-a919-60874442186a">

Release Notes:

- Improved the design of the feedback dialog.

This PR fixes the border color used when the email input in the feedback
dialog is invalid.

Previously this was hardcoded just to `red` instead of using the
appropriate color from the theme.

<img width="653" alt="Screenshot 2024-01-08 at 5 40 07 PM"
src="https://github.com/zed-industries/zed/assets/1486634/ea01cd76-d661-4512-b668-c82b8d00d84e">

Release Notes:

- Fixed the border color used for the email input in the feedback dialog
when an invalid email is entered.

- First pass of real access control
- Check user is host for host-broadcasted project messages
- Only allow read-write users to update buffers

[[PR Description]]

Release Notes:

- (Added|Fixed|Improved) ...
([#<public_issue_number_if_exists>](https://github.com/zed-industries/community/issues/<public_issue_number_if_exists>)).

Release Notes:

- Fixed a crash that could occur when creating files with '..' in the
path

Co-Authored-By: Max <max@zed.dev>

This essentially shaves off about 10% off of an incremental build after
project change and potentially more if you're changing stuff like
`welcome` that's very close to the `zed` crate in the dep graph. That's
because macro expansion takes place even in incremental builds it seems?
And zed (lib) + zed (bin) could take up to 4 seconds out of an
incremental build, which is a *lot* in a 10s build. In reality though it
shaves 1 second off of 5 seconds incremental 'welcome'/ 1s off of 10s
'project' builds.

Note that we had `assets` crate in the past (removed in #2575 /cc
@maxbrunsfeld), but this is a bit different, because `assets` is a
dependency of *just* zed and nothing else. We essentially cache macro
expansion results ourselves.

Release Notes:

- N/A

This PR styles the message input in the chat panel.

<img width="242" alt="Screenshot 2024-01-08 at 4 28 33 PM"
src="https://github.com/zed-industries/zed/assets/1486634/48e83692-878e-4891-8e40-8738cdeb23a8">

Release Notes:

- Improved the styling of the message editor in the chat panel.

Co-Authored-By: Max <max@zed.dev>

[[PR Description]]

Release Notes:

- (Added|Fixed|Improved) ...
([#<public_issue_number_if_exists>](https://github.com/zed-industries/community/issues/<public_issue_number_if_exists>)).

This PR improves the empty states for the chat panel:

- The signed-out state has been updated to match our other signed-out
panel states.
- A new state has been added to account for the case where a user is
signed in but doesn't have an active chat.

Release Notes:

- Improved the design of empty states in the chat panel.

Co-Authored-By: Max <max@zed.dev>

Deals with https://github.com/zed-industries/community/issues/2383

Release Notes:

- Fixed context menu not shown when right clicking empty project panel
space

Release Notes:

- Fixed outline selections not being cleared on certain modal dismiss
actions

Currently when one runs `cargo build` twice without changing anything,
zed lib and binary are gonna get rebuilt every time. I checked out cargo
logs and it turns out we were querying wrong path to `.git/logs/HEAD` in
our build.rs, causing it to rerun on every build and thus marking zed
lib as dirty.

See logs (`CARGO_LOG=cargo::core::compiler::fingerprint=trace cargo
build`):
```
0.501173792s  INFO cargo::core::compiler::fingerprint: fingerprint dirty for zed v0.120.0 (/Users/hiro/Projects/zed/crates/zed)/RunCustomBuild/TargetInner { ..: custom_build_target("build-script-build", "/Users/hiro/Projects/zed/crates/zed/build.rs", Edition2021) }
0.501180417s  INFO cargo::core::compiler::fingerprint:     dirty: FsStatusOutdated(StaleItem(MissingFile("/Users/hiro/Projects/zed/crates/zed/.git/logs/HEAD")))
```
The path to .git directory is relative to crates/zed and not to the
workspace's root.

/cc @maxbrunsfeld 

Release Notes:
- N/A

This PR fixes the inconsistent sizing between the buffer search and the
project search when both elements have both a primary and secondary item
shown in the toolbar.

Release Notes:

- Fixed some inconsistent sizing in the buffer search and project search
when both have two rows of tools in the toolbar.

Co-Authored-By: Max<max@zed.dev>

This PR removes a commented-out implementation for the `ActiveTheme`
trait on the `WindowContext`.

We don't need this implementation as we can go through the
`AppContext`'s implementation.

Release Notes:

- N/A

This PR removes a resolved TODO in the `terminal` crate.

Release Notes:

- N/A

This PR cleans up the doc comment for the `rgb_for_index` function.

Release Notes:

- N/A

Updates Zed2 Copilot UI

- Introduces the `Headline` component for rendering large text
- Styles the 3 Copilot prompt states

![CleanShot 2024-01-08 at 13 19
09@2x](https://github.com/zed-industries/zed/assets/1714999/4b58b85f-23aa-4c22-9ca6-d0abd232cf18)
![CleanShot 2024-01-08 at 13 18
55@2x](https://github.com/zed-industries/zed/assets/1714999/0bf71e1d-63b5-4fbb-8672-e42f8602516d)


Release Notes:

- Updated the connect Copilot modal UI.

Let this screenshot of settings.json speak for itself: 

![image](https://github.com/zed-industries/zed/assets/24362066/fca60383-1788-43f9-803b-00f083394c8a)

Release Notes:
- Added code completion & on-hover documentation to Zed's settings.json
file.

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

This PR fixes the layout shift that would occur in the channel list when
opening a rename editor for a channel.

Release Notes:

- Fixed layout shift when opening a rename editor for a channel.

This PR adjusts the spacing of the indicator showing the number of extra
call participants that appears after the facepile:

<img width="242" alt="Screenshot 2024-01-08 at 1 09 39 PM"
src="https://github.com/zed-industries/zed/assets/1486634/6d9cbefa-3b4e-4501-ab11-51026dfb5b6c">

Release Notes:

- Added more space between the call participant facepile and the number
indicating additional call participants.

This PR removes a resolved TODO in drawing diff hunk status.

Release Notes:

- N/A

I've missed a single run_until_parked call. mb

Release Notes:

- N/A

This PR updates the indicator for changes within a fold to use the
correct color from the theme:

<img width="380" alt="Screenshot 2024-01-08 at 12 52 56 PM"
src="https://github.com/zed-industries/zed/assets/1486634/b8bf6bf3-6acc-43a4-8c4b-a02c975c7f02">

Release Notes:

- Updated the color of the indicator for a fold containing modified
lines.

This PR updates the styling of the tree branches in the current call
section of the collab panel:

- Fixed the gap between the notes and chat items.
- We now overdraw the tree branch on the notes item so it fills the gap.
- The tree branch lines are now thinner.

<img width="231" alt="Screenshot 2024-01-08 at 12 35 35 PM"
src="https://github.com/zed-industries/zed/assets/1486634/844c9e18-c2de-4163-9384-41d1577e23a0">

Note: I think the signature for `render_tree_branch` could use some
improvement. I don't like having the multiple `bool` parameters, but any
change I could think of was going to be a bit more invasive than I
wanted to take on in this PR.

Release Notes:

- Improved the style of the tree branches in current call details in the
collab panel.

Commenting this one out temporarily to not break CI for folks while I
look into it.
Release Notes:

- N/A