Editor toolbar configuration (#7338)

Adds settings for hiding breadcrumbs and quick action bar from
the editor toolbar. If both elements are hidden, the toolbar disappears
completely.

Example:

```json
"toolbar": {
  "breadcrumbs": true,
  "quick_actions": false
}
```

- It intentionally doesn't hide breadcrumbs in other views (for
instance, in the search result window) because their usage there differ
from the main editor.
- The editor controls how breadcrumbs are displayed in the toolbar, so
implementation differs a bit for breadcrumbs and quick actions bar.

Release Notes:

- Added support for configuring the editor toolbar ([4756](https://github.com/zed-industries/zed/issues/4756))

crates/editor/src/editor_settings.rs

@@ -10,6 +10,7 @@ pub struct EditorSettings {
     pub show_completion_documentation: bool,
     pub completion_documentation_secondary_query_debounce: u64,
     pub use_on_type_format: bool,
+    pub toolbar: Toolbar,
     pub scrollbar: Scrollbar,
     pub vertical_scroll_margin: f32,
     pub relative_line_numbers: bool,
@@ -29,6 +30,12 @@ pub enum SeedQuerySetting {
     Never,
 }
 
+#[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
+pub struct Toolbar {
+    pub breadcrumbs: bool,
+    pub quick_actions: bool,
+}
+
 #[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
 pub struct Scrollbar {
     pub show: ShowScrollbar,
@@ -86,6 +93,8 @@ pub struct EditorSettingsContent {
     ///
     /// Default: true
     pub use_on_type_format: Option<bool>,
+    /// Toolbar related settings
+    pub toolbar: Option<ToolbarContent>,
     /// Scrollbar related settings
     pub scrollbar: Option<ScrollbarContent>,
 
@@ -110,6 +119,19 @@ pub struct EditorSettingsContent {
     pub redact_private_values: Option<bool>,
 }
 
+// Toolbar related settings
+#[derive(Clone, Default, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
+pub struct ToolbarContent {
+    /// Whether to display breadcrumbs in the editor toolbar.
+    ///
+    /// Default: true
+    pub breadcrumbs: Option<bool>,
+    /// Whether to display quik action buttons in the editor toolbar.
+    ///
+    /// Default: true
+    pub quick_actions: Option<bool>,
+}
+
 /// Scrollbar related settings
 #[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
 pub struct ScrollbarContent {