Add buffer path to the prompt.

Z-2903

Release Notes:
- Added a "Save all/Discard all" prompt when closing a pane with
multiple edited buffers.

Improve settings interface to local LSP

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

This PR restructures the `ui` crate into just `elements` and
`components`.

This was already done on the `gpui2-ui` branch, just getting it onto
`main`.

Release Notes:

- N/A

---------

Co-authored-by: Nate Butler <nate@zed.dev>

This PR mainlines the `Icon` and `IconButton` changes from the
`gpui2-ui` branch.

Release Notes:

- N/A

Co-authored-by: Nate Butler <nate@zed.dev>

This PR updates the storybook CLI to support displaying all of the
available stories.

The `--help` flag will now show a list of all the available stories:

<img width="1435" alt="Screenshot 2023-09-22 at 6 11 00 PM"
src="https://github.com/zed-industries/zed/assets/1486634/284e1a24-46ec-462e-9709-0f9b6e94931f">

Inputting an invalid story name will also show the list of available
stories:

<img width="1435" alt="Screenshot 2023-09-22 at 6 10 43 PM"
src="https://github.com/zed-industries/zed/assets/1486634/1ce3ae3f-ab03-4976-a06a-5a2b5f61eae3">

Release Notes:

- N/A

This PR scaffolds the `Toolbar` and `Breadcrumb` components.

Right now they both just consist of hardcoded data.

<img width="846" alt="Screenshot 2023-09-22 at 4 54 00 PM"
src="https://github.com/zed-industries/zed/assets/1486634/70578df2-7216-42d2-97ef-d38b83fb4a25">

<img width="799" alt="Screenshot 2023-09-22 at 4 46 04 PM"
src="https://github.com/zed-industries/zed/assets/1486634/73ca3d8a-baf9-4ed4-b4c4-279c674672a3">

Release Notes:

- N/A

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

This PR updates the UI component stories to label the various states
that they are in.

Release Notes:

- N/A

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

This PR improves the error message when `FontCache.load_family` attempts
to load a font that is not present on the system.

I ran into this while trying to run the `storybook` for the first time.
The error message indicated that a font family was not found, but did
not provide any information as to which font family was being loaded.

### Before

```
   Compiling storybook v0.1.0 (/Users/maxdeviant/projects/zed/crates/storybook)
    Finished dev [unoptimized + debuginfo] target(s) in 8.52s
     Running `/Users/maxdeviant/projects/zed/target/debug/storybook`
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: could not find a non-empty font family matching one of the given names', crates/theme/src/theme_settings.rs:132:18
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
libc++abi: terminating due to uncaught foreign exception
fish: Job 1, 'cargo run' terminated by signal SIGABRT (Abort)
```

### After

```
   Compiling storybook v0.1.0 (/Users/maxdeviant/projects/zed/crates/storybook)
    Finished dev [unoptimized + debuginfo] target(s) in 7.90s
     Running `/Users/maxdeviant/projects/zed/target/debug/storybook`
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: could not find a non-empty font family matching one of the given names: `Zed Mono`', crates/theme/src/theme_settings.rs:132:18
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
libc++abi: terminating due to uncaught foreign exception
fish: Job 1, 'cargo run' terminated by signal SIGABRT (Abort)
```

Release Notes:

- N/A

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

This PR removes the need for writing manual mappings in the `FromStr`
implementation for the `StorySelector` enum used in the storybook CLI.

We are now using the
[`EnumString`](https://docs.rs/strum/0.25.0/strum/derive.EnumString.html)
trait from `strum` to automatically derive snake_cased names for the
enums.

This will cut down on some of the manual work needed to wire up more
stories to the storybook.

Release Notes:

- N/A

This PR puts the `Theme` returned from the `theme` function behind an
`Arc`.

### Motivation

While working on wiring up window focus events for the `TitleBar`
component we ran into issues where `theme` was holding an immutable
borrow to the `ViewContext` for the entirety of the `render` scope,
which prevented having mutable borrows in the same scope.

### Explanation

To avoid this, we can make `theme` return an `Arc<Theme>` to allow for
cheap clones and avoiding the issues with the borrow checker.

Release Notes:

- N/A

Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>

This PR factors out the bulk of the boilerplate required to setup a
story in the storybook out into separate components.

The pattern we're using here is adapted from the "[associated
component](https://maxdeviant.com/posts/2021/react-associated-components/)"
pattern in React.

Release Notes:

- N/A

Reorganized assistant/semantic_index crates and introduced AI crate to
include shared functionality.

Release Notes:

- Moved most of the Assistant functionality from ai crate to assistant
crate
- Moved interaction with embedding providers from semantic_index to ai
crate

Last follow-up of https://github.com/zed-industries/zed/pull/3002
Fixes
https://zed-industries.slack.com/archives/C04S6T1T7TQ/p1695281196667609

Copilot sends multiple events about its LSP server readiness, not
necessarily recreating the server from scratch (e.g. due to re-sign in
action). Avoid re-adding same log subscriptions on the same LSP server,
which causes panics.

Release Notes:

- N/A

Copilot sends multiple events about its LSP server readiness, not necessarily recreating the server from scratch (e.g. due to re-sign in action).
Avoid re-adding same log subscriptions on the same LSP server, which
causes panics.

Merges various in-progress gpui2 component branches with the new `ui`
crate.

This PR adds a `TrafficLights` component for GPUI2.

<img width="861" alt="Screenshot 2023-09-21 at 11 32 10 PM"
src="https://github.com/zed-industries/zed/assets/1486634/0fe0e847-49b3-44dc-bd4c-64f12f0051c1">

Release Notes:

- N/A

This PR updates the `storybook` with support for adding stories for
individual components.

### Motivation

Right now we just have one story in the storybook that renders an entire
`WorkspaceElement`.

While iterating on the various UI components, it will be helpful to be
able to create stories of those components just by themselves.

This is especially true for components that have a number of different
states, as we can render the components in all of the various states in
a single layout.

### Explanation

We achieve this by adding a simple CLI to the storybook.

The `storybook` binary now accepts an optional `[STORY]` parameter that
can be used to indicate which story should be loaded. If this parameter
is not provided, it will load the workspace story as it currently does.

Passing a story name will load the corresponding story, if it exists.

For example:

```
cargo run -- elements/avatar
```

<img width="723" alt="Screenshot 2023-09-21 at 10 29 52 PM"
src="https://github.com/zed-industries/zed/assets/1486634/5df489ed-8607-4024-9c19-c5f4541f97c9">

```
cargo run -- components/facepile
```

<img width="785" alt="Screenshot 2023-09-21 at 10 30 07 PM"
src="https://github.com/zed-industries/zed/assets/1486634/e04a4577-7403-405d-b23c-e765b7a06229">



Release Notes:

- N/A

Fixes an ambiguous reference to `theme` causing storybook not to build.