Allow configuring spacing of project panel entries (#16255)

Release Notes:

- Added `project_panel.entry_spacing` setting to configure spacing
between entries in the project panel.

### Comfortable (default)
```json
  "project_panel": {
    "entry_spacing": "comfortable",
```
<img width="1582" alt="Screenshot 2024-08-14 at 5 50 41 PM"
src="https://github.com/user-attachments/assets/3411a82e-7517-4095-bf4a-bbf40000a7cb">

### Standard
```json
  "project_panel": {
    "entry_spacing": "standard",
```
<img width="1582" alt="Screenshot 2024-08-14 at 5 50 54 PM"
src="https://github.com/user-attachments/assets/2c13d799-c405-4301-8214-1cb3cc641c92">

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

crates/project_panel/src/project_panel_settings.rs

@@ -18,11 +18,22 @@ pub enum ShowIndentGuides {
     Never,
 }
 
+#[derive(Copy, Clone, Debug, Default, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum EntrySpacing {
+    /// Comfortable spacing of entries.
+    #[default]
+    Comfortable,
+    /// The standard spacing of entries.
+    Standard,
+}
+
 #[derive(Deserialize, Debug, Clone, Copy, PartialEq)]
 pub struct ProjectPanelSettings {
     pub button: bool,
     pub default_width: Pixels,
     pub dock: ProjectPanelDockPosition,
+    pub entry_spacing: EntrySpacing,
     pub file_icons: bool,
     pub folder_icons: bool,
     pub git_status: bool,
@@ -90,6 +101,10 @@ pub struct ProjectPanelSettingsContent {
     ///
     /// Default: left
     pub dock: Option<ProjectPanelDockPosition>,
+    /// Spacing between worktree entries in the project panel.
+    ///
+    /// Default: comfortable
+    pub entry_spacing: Option<EntrySpacing>,
     /// Whether to show file icons in the project panel.
     ///
     /// Default: true