The goal of this PR is to make Following more intuitive.

### Old Behavior

Previously, following was scoped to a project. In order to follow
someone in a given window, the window needed to contain a shared
project, and the leader needed to be present in the project. Otherwise,
following failed.

### New Behavior

* You can always follow **any** participant in the current call, in any
pane of any window.
* When following someone in a project that you're both collaborating in,
it works the same as before.
* When following someone in an unshared project, or a project that they
don't have open, you'll only get updates about the leader's views that
don't belong to a project, such as channel notes views. When the leader
focuses a file in a different project, you'll get the "follow $LEADER to
their active project" indicator

### Todo

* [x] Change db schema and RPC protocol so a project id isn't required
for following
* [x] Change client to allow following into non-project items regardless
of the leader's project
* [x] Assign colors to users in a way that doesn't require users to be
in a shared project.

This PR is a bit of a last minute change, but I realized there was
actually a third player in the Elixir LSP space who wants support as
well,
[lexical](https://github.com/zed-industries/community/issues/1567). I
realized that the settings arrangement I shipped in this preview
precludes adding a third kind of LSP. I don't have the time to learn how
to fully support this LSP, but I thought I'd at least refactor how the
settings are represented before this hits stable.

Release Notes:

- Changed the new `"elixir": { "next": "on" }` setting to `"elixir": {
"lsp": "next_ls" }`. The `elixir.lsp` setting requires a full restart to
take effect. (Preview only)

This makes zed always behave as if the app is active, even if no window is focused.
It prevents the 'viewing a window outside of zed' state during collaboration.

Release Notes:

- vim: Fix a bug where following could put you in visual mode

fixes https://github.com/zed-industries/community/issues/2098

Release Notes:

- Fixed a bug in Zed's LSP implementation when using Next LS.

add scheme as a parseable file type in semantic index.
Each file will operate as a single embedding, in which no real scheme
syntax or tree-sitter level data is stored.

Release Notes:

- Added scheme to Semantic Index

This PR fixes the glyph used for the option key in the new `Keybinding`
component.

Same fix as in #3065, but applied to the new `Keybinding` component so
that we don't regress when switching to GPUI2.

<img width="750" alt="Screenshot 2023-09-29 at 10 50 15 AM"
src="https://github.com/zed-industries/zed/assets/1486634/8c6147e9-fa05-4804-954c-b8e3b98cbdf0">

Release Notes:

- N/A

![image](https://github.com/zed-industries/zed/assets/24362066/94731737-a21a-4cef-a445-eb855f1a4d3e)

![image](https://github.com/zed-industries/zed/assets/24362066/e879ec9a-70aa-4989-923f-4cca18d01587)

Release Notes:

- Fixed option key's appearance in keybindings

![CleanShot 2023-09-27 at 18 09
37](https://github.com/zed-industries/zed/assets/482957/317d31e4-81f8-44d8-b94f-8ca7150d3fd2)

Release Notes:

- Added the ability to exclude warnings from project diagnostics. By
default, they will be on but they can be disabled temporarily by
clicking on the warnings icon. The default behavior can be changed by
changing the new `diagnostics.include_warnings` setting.

This PR fixes the kitchen sink story in the storybook.

Included are some additional changes that make it so the kitchen sink is
automatically populated by all of the defined stories.

Release Notes:

- N/A

This PR mainlines the current state of new GPUI2-based UI from the
`gpui2-ui` branch.

Release Notes:

- N/A

---------

Co-authored-by: Nate Butler <iamnbutler@gmail.com>
Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
Co-authored-by: Marshall Bowers <1486634+maxdeviant@users.noreply.github.com>
Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>
Co-authored-by: Nate <nate@zed.dev>
Co-authored-by: Mikayla <mikayla@zed.dev>

Release Notes:

- vim: Fix `dw` on the last word of a line, and on empty lines.

Release Notes:

- vim: Add ctrl-i to go forward
([#1732](https://github.com/zed-industries/community/issues/1732)).
ctrl-o was already supported.
- vim: Add `g <space>` to open the current snippet in its own file.
- vim: Escape will now return to normal mode even if completion menus
are open (use `ctrl-x ctrl-z` to hide menus, as in vim).
- vim: Add key bindings for Zed's various completion mechanisms:
- - `ctrl-x ctrl-o` to open the completion menu,
- -  `ctrl-x ctrl-l` to open the LSP action menu,
- - `ctrl-x ctrl-c` to trigger Copilot (requires configuring copilot),
- - `ctrl-x ctrl-a` to trigger the inline Assistant (requires
configuring openAI),

NOTE: we should add these to the docs before shipping 0.107 to stable.

- vim: add ctrl-a/ctrl-x for increment/decrement

Release Notes:

- Enabled the `semantic_index` setting by default.

Following works without a project, but following in unshared projects does
not need to be replicated to other participants.

Rows representing pending participants have a null participant_index.

Co-authored-by: Conrad <conrad@zed.dev>

Co-authored-by: Conrad <conrad@zed.dev>

Co-authored-by: Conrad <conrad@zed.dev>

Co-authored-by: Conrad <conrad@zed.dev>
Co-authored-by: Antonio <antonio@zed.dev>

If you highlight the following block of text (with a single selection):

```
The quick brown
fox jumps over
the lazy dog
```

and run `editor: convert to upper camel case`, you'll get:

```
TheQuickBrown
foxJumpsOver
theLazyDog
```

instead of:

```
TheQuickBrown
FoxJumpsOver
TheLazyDog
```

The same thing happens for `editor: convert to title case`. This happens
because [`to_case` crate](https://crates.io/crates/convert_case) doesn't
allow the user to define '\n' as a boundary. I wanted to fix this at the
lib level, so I filled [an
issue](https://github.com/rutrum/convert-case/issues/16) but I never
heard back. What's strange is VS Code and Sublime I think both exhibit
the same output as we do currently, but I don't personally think this
feels right (happy to hear opposing opinions). I'm just doing the naive
thing to hack around this limitation of the `to_case` crate.

I did some testing and it seems I only need to adjust `editor: convert
to title case` and `editor: convert to upper camel case`. The way the
other transformations are implemented in `to_case` don't seem to have
this issue.

Release Notes:

- Fixed a bug where running certain text transfomration commands on a
single selection covering multiple lines would not transform all
selected lines as expected.

Deals with https://github.com/zed-industries/community/issues/2086
Part of https://github.com/zed-industries/community/issues/351

Initial:
<img width="585" alt="Screenshot 2023-09-28 at 09 50 05"
src="https://github.com/zed-industries/zed/assets/2690773/e0149312-dfe3-4b7c-948c-0f593d6f540c">
First query letter input (only two history items match that, both are
preserved on top, with their order preserved also)
<img width="603" alt="Screenshot 2023-09-28 at 09 50 08"
src="https://github.com/zed-industries/zed/assets/2690773/85ab2f4c-bb9c-4811-b8b0-b5c14a370ae2">
Second query letter input, no matching history items:
<img width="614" alt="Screenshot 2023-09-28 at 09 50 11"
src="https://github.com/zed-industries/zed/assets/2690773/6d380403-a43c-4f00-a05b-88f43f91fefb">
Remove second query letter, history items match again and pop to the
top:
<img width="574" alt="Screenshot 2023-09-28 at 09 50 15"
src="https://github.com/zed-industries/zed/assets/2690773/5981ca53-6bc8-4305-ae36-27144080e1a2">


* allows `file_finder::Toggle` (cmd-p by default) to cycle through file
finder items (ESC closes the modal still)
* on query typing, preserve history items that match the query and keep
them on top, with their ordering preserved
* show history items' matched letters

Release Notes:

- Improve file finder ergonomics: allow cycle through items with the
toggle action, preserve matching history items on query input