project_panel: Add hide_root when only one folder in the project (#25289)

Closes #24188

Todo:
- [x] Hide root when only one worktree
- [x] Basic tests
- [x] Docs
- [x] Fix `select_first` + tests
- [x] Fix auto collapse dir + tests
- [x] Fix file / dir creation + tests
- [x] Fix root rename case

| Show root | Hide root |
|--------|--------|
| <img width="272" alt="Screenshot 2025-02-20 alle 22 35 55"
src="https://github.com/user-attachments/assets/361d93c7-e1ad-4419-a5f4-be62c9632807"
/> | <img width="269" alt="Screenshot 2025-02-20 alle 22 36 11"
src="https://github.com/user-attachments/assets/62011f76-a24b-4297-9734-f5c3b9f75760"
/> |
| <img width="275" alt="Screenshot 2025-02-20 alle 22 56 33"
src="https://github.com/user-attachments/assets/77e7e6e6-3dfe-4e88-b4b0-b620cb809d2b"
/> | <img width="267" alt="Screenshot 2025-02-20 alle 22 55 53"
src="https://github.com/user-attachments/assets/fa1099c8-7ed0-45ef-a7cf-aeb54b8283b1"
/> |


Release Notes:

- Added support to hide the root entry of the Project Panel when there’s
only one folder in the project. This can be enabled by setting
`hide_root` to `true` in the `project_panel` config.

---------

Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>

crates/project_panel/src/project_panel_settings.rs

@@ -44,6 +44,7 @@ pub struct ProjectPanelSettings {
     pub auto_fold_dirs: bool,
     pub scrollbar: ScrollbarSettings,
     pub show_diagnostics: ShowDiagnostics,
+    pub hide_root: bool,
 }
 
 #[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
@@ -145,6 +146,10 @@ pub struct ProjectPanelSettingsContent {
     pub show_diagnostics: Option<ShowDiagnostics>,
     /// Settings related to indent guides in the project panel.
     pub indent_guides: Option<IndentGuidesSettingsContent>,
+    /// Whether to hide the root entry when only one folder is open in the window.
+    ///
+    /// Default: false
+    pub hide_root: Option<bool>,
 }
 
 impl Settings for ProjectPanelSettings {