git_ui: Update commit composer and git status entry UI (#22738)

Blocked on:

- No way to get # of lines changed (added/removed)
- Need methods for:
    - `commit`
    - `stage`
    - `unstage`
- `revert_all` - Similar to Editor::RevertFile, but for all changes in
the project

TODO:

- [ ] Update checkbox visual style to match
[figma](https://www.figma.com/design/sKk3aa7XPwBoE8fdlgp7E8/Git-integration?node-id=804-9255&t=wsHFxPgYHEX78Ky1-11)
- [ ] Update panel button style to filled

- [ ] Panel header
  - [x] Correct 1 change suffix (1 changes -> 1 change)
  - [ ] Add lines changed badge
  - [ ] Add context menu button (`...`)
  - [ ] Add context menu
  - [ ] Wire up Revert All
- [ ] Entry List
  - [x] Revert unwanted ListItem styling
  - [x] Add selected, hover states
  - [ ] Add `scrolled_to_top`, `scrolled_to_bottom`
  - [ ] Show gradient overflow indicator
- [ ] Add `JumpToTop`, `JumpToBottom` actions to the list, bind to shift
+ arrow keys
  - [ ] Remove wrapping from keyboard movement
- [ ] Entry
  - [x] Style deleted entries with a strikethrough
  - [x] `...` on hover or selected
  - [ ] Add context menu
- [ ] Composer
  - Todo...
  
Release Notes:

- N/A

Cargo.lock

@@ -5178,8 +5178,10 @@ dependencies = [
  "anyhow",
  "collections",
  "db",
+ "editor",
  "git",
  "gpui",
+ "language",
  "menu",
  "project",
  "schemars",
@@ -5187,6 +5189,7 @@ dependencies = [
  "serde_derive",
  "serde_json",
  "settings",
+ "theme",
  "ui",
  "util",
  "windows 0.58.0",