git_ui: Add Git Panel settings (#23132)

This PR adds settings for the Git Panel.

The new settings include:

| Setting | Description | Default |
|---------|-------------|---------|
| `git_panel.button` | Toggle visibility of the Git Panel button in the
status bar | `true` |
| `git_panel.dock` | Choose where to dock the Git Panel | `"left"` |
| `git_panel.default_width` | Set the default width of the Git Panel in
pixels | `360` |
| `git_panel.status_style` | Select how Git status is displayed |
`"icon"` |
| `git_panel.scrollbar.show` | Configure scrollbar behavior | Inherits
from editor settings |

Example usage:

```json
"git_panel": {
  "button": true,
  "dock": "left",
  "default_width": 360,
  "status_style": "icon",
  "scrollbar": {
    "show": "auto"
  }
}
```

Release Notes:

- N/A

crates/git_ui/src/git_ui.rs

@@ -2,9 +2,9 @@ use ::settings::Settings;
 use collections::HashMap;
 use futures::{future::FusedFuture, select, FutureExt};
 use git::repository::{GitFileStatus, GitRepository, RepoPath};
+use git_panel_settings::GitPanelSettings;
 use gpui::{actions, AppContext, Context, Global, Hsla, Model, ModelContext};
 use project::{Project, WorktreeId};
-use settings::GitPanelSettings;
 use std::sync::mpsc;
 use std::{
     pin::{pin, Pin},
@@ -16,7 +16,7 @@ use ui::{Color, Icon, IconName, IntoElement, SharedString};
 use worktree::RepositoryEntry;
 
 pub mod git_panel;
-mod settings;
+mod git_panel_settings;
 
 const GIT_TASK_DEBOUNCE: Duration = Duration::from_millis(50);