This PR updates the `ThemeStyles` struct to use the `Refineable` trait
instead of a custom declarative macro for generating refinements.

Release Notes:

- N/A

This PR removes the old `Theme` definition in favor of the new
`ThemeVariant`s.

The new `SyntaxStyles` have been reverted to the old `SyntaxTheme` that
operates by storing the syntax styles as a vector of
`gpui2::HighlightStyle`s.

This is necessary for the intended usage by `language2`, where we find
the longest key in the theme's syntax styles that matches the capture
name:

https://github.com/zed-industries/zed/blob/18431051d9d750d9e66284a71f7a55a1e31c1374/crates/language2/src/highlight_map.rs#L15-L41

This PR reworks the theme definition in the `theme2` crate to be based
off of the new theme work that @iamnbutler has been working on.

We're still developing the new theme system, but it is complete enough
that we can now load the default theme and use it to theme the storybook
(albeit with some further refining of the color palette required).

---------

Co-authored-by: Nate Butler <iamnbutler@gmail.com>
Co-authored-by: Marshall Bowers <marshall@zed.dev>

Co-authored-by: Marshall <marshall@zed.dev>

PR to get zed2 into main.

Because we have taken the approach of porting crates by renaming them to
`-2` we will need to manually reapply any changes that were made to
ported crates since the `zed2` branch diverged from master.

I think this is the list of PRs that may need changes ported manually.
Any changes to the following crates may need to be moved from crate `x`
to `x2` for each of the following crates: `audio call client copilot db
feature_flags fs fuzzy gpui install_cli language lsp prettier project
rpc settings storybook terminal theme ui zed`.

- [x] f75eb3f62 Conrad Irwin (origin/main, origin/HEAD, main) Merge
branch 'more-signing' (17 hours ago)
- [x] 832026a0a Julia Limit language server reinstallation attempts
(#3177) (18 hours ago)
- [x] 4539cef6d Julia Capture language server stderr during startup/init
and log if failure (#3175) (21 hours ago)
- [x] e6f2288a0 Conrad Irwin Don't use function_name in vim tests
(#3171) (2 days ago)
- [x] f67f42779 Mikayla Maki Rename IIFE to maybe (#3165) (2 days ago)
- [ ] 90f65ec9f Max Brunsfeld Remove logic for multiple channel parents
(#3162) (2 days ago)
- [ ] 4f859e025 Conrad Irwin link to channel notes (#3167) (2 days ago)
- [ ] b8bd070a8 Conrad Irwin Fix panic by disallowing multiple room
joins (#3149) (3 days ago)
- [ ] cc9e92857 Max Brunsfeld Guest roles (#3140) (3 days ago)
- [x] b090cefdd Kirill Bulatov Rework prettier tests (#3160) (3 days
ago)
- [ ] ff497810d Kyle Caverly move keychain access into semantic index as
opposed to on init (#3158) (3 days ago)
- [x] 2b95db087 Conrad Irwin Fix infinite loop in select all (#3154) (3
days ago)
- [ ] a5836b033 Max Brunsfeld Add chat mentions and a notifications
panel (#3121) (4 days ago)
- [ ] ef1a69156 Kyle Caverly update semantic search to use keychain as
fallback (#3151) (6 days ago)
- [x] 26638748b Kirill Bulatov Move prettier parsers data into languages
from LSP adapters (#3150) (6 days ago)
- [ ] 0dae0f602 Conrad Irwin pixel columns (#3052) (7 days ago)
- [x] cc7df91cc Julia Whoops (#3146) (7 days ago)
- [x] 808976ee2 Julia Magic incantations for Tailwind autocomplete in
more languages (#3141) (7 days ago)
- [ ] cc390ba86 Conrad Irwin Start writing role to database (#3120) (10
days ago)
- [ ] 2795091f0 Kyle Caverly Introduce Context Retrieval in Inline
Assistant (#3097) (10 days ago)
- [x] b168bded1 Conrad Irwin New entitlements: (#3118) (10 days ago)
- [x] 247cdb1e1 Joseph T. Lyons Fix telemetry-related crash on start up
(#3131) (11 days ago)
- [ ] 2323fd17b Julia Autocomplete docs (#3126) (2 weeks ago)
- [x] 16d9d77d8 Kirill Bulatov Update diagnostics indicator when
diagnostics are udpated (#3128) (2 weeks ago)
- [ ] 634202340 Kirill Bulatov Remove zed -> ... -> semantic_index ->
zed Cargo dependency cycle (#3127) (2 weeks ago)

Note: this list does not include any PRs that did not change crates that
have been converted; it also does not include any commits that were
pushed directly to master.

### To figure out what needs migrating, run:

```
git diff COMMIT^..COMMIT -- crates/audio crates/call crates/client crates/copilot crates/db crates/feature_flags crates/fs crates/fuzzy crates/gpui crates/install_cli crates/language crates/lsp crates/prettier crates/project crates/rpc crates/settings crates/storybook crates/terminal crates/theme crates/ui crates/zed
```

I'm not sure these are strictly necessary, but it will make porting
tests easier to have them.

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

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

Co-Authored-By: Kirill <kirill@zed.dev>

In gpui1 we used to do this even outside of top-level contexts, but not
sure we should make tests work that differently to the main app.

Co-Authored-By: Kirill <kirill@zed.dev>

The entity map needs to be able to distinguish between the case when
the entity_id is waiting to be dropped, and when it is completely gone.

Before 8bc207141, it assumed that entity_ids in dropped_entity_ids could
be re-used. This caused `take_dropped` to error because the slot had
been overwritten. The fix there caused weak handles to allow upgrading
a reference count from 0, which could resurrect items in
`dropped_entity_ids` which caused them to be dropped twice.

We could allow weak items to upgrade from 0, and delete from
dropped_entity_ids, but that seemed more complicated than necessary.

Ports https://github.com/zed-industries/zed/pull/3191 to zed2

Deals with zed-industries/community#2191
Fix Zed starting too many prettier installations in the beginning, and not being able to format the config files.

Deals with https://github.com/zed-industries/community/issues/2191

Fix Zed starting too many prettier installations in the beginning, and
not being able to format the config files.

Release Notes:

- Fixed prettier not being able to format Zed's config files and spawning excessive prettier installations

Adds an `Entity` trait for abstracting over `View`s and `Model`s, and
implements it for the `subscribe()` and `observe()` APIs.

The last commit also includes a fun experiment I added, using the
`Result` type to return the owned model handles back to the caller in
the case of downcast failure, inspired by the `binary_search*` methods.

Part of https://github.com/zed-industries/zed/pull/3128 that is possible
to apply now.

@SomeoneToIgnore I had to port
https://github.com/zed-industries/zed/pull/3150 to zed2 in the process,
giving you a heads-up