Restore notification panel settings (#37661)

Follow-up to https://github.com/zed-industries/zed/pull/37489

Notification panel settings were always missing the content, hence this
PR adds it. After #37489, the use of the same content twice broke
things, which currently makes the notification panel non-configurable on
Nightly. This PR fixes this.

There once was an issue about the documentation for the panel being
wrong as well. However, I was just unable to find that sadly.

Release Notes:

- N/A

crates/collab_ui/src/panel_settings.rs

@@ -44,14 +44,6 @@ pub struct ChatPanelSettingsContent {
     pub default_width: Option<f32>,
 }
 
-#[derive(Deserialize, Debug, SettingsKey)]
-#[settings_key(key = "notification_panel")]
-pub struct NotificationPanelSettings {
-    pub button: bool,
-    pub dock: DockPosition,
-    pub default_width: Pixels,
-}
-
 #[derive(Clone, Default, Serialize, Deserialize, JsonSchema, Debug, SettingsUi, SettingsKey)]
 #[settings_key(key = "collaboration_panel")]
 pub struct PanelSettingsContent {
@@ -69,6 +61,30 @@ pub struct PanelSettingsContent {
     pub default_width: Option<f32>,
 }
 
+#[derive(Deserialize, Debug)]
+pub struct NotificationPanelSettings {
+    pub button: bool,
+    pub dock: DockPosition,
+    pub default_width: Pixels,
+}
+
+#[derive(Clone, Default, Serialize, Deserialize, JsonSchema, Debug, SettingsUi, SettingsKey)]
+#[settings_key(key = "notification_panel")]
+pub struct NotificationPanelSettingsContent {
+    /// Whether to show the panel button in the status bar.
+    ///
+    /// Default: true
+    pub button: Option<bool>,
+    /// Where to dock the panel.
+    ///
+    /// Default: right
+    pub dock: Option<DockPosition>,
+    /// Default width of the panel in pixels.
+    ///
+    /// Default: 300
+    pub default_width: Option<f32>,
+}
+
 #[derive(Clone, Default, Serialize, Deserialize, JsonSchema, Debug, SettingsUi, SettingsKey)]
 #[settings_key(key = "message_editor")]
 pub struct MessageEditorSettings {
@@ -106,7 +122,7 @@ impl Settings for ChatPanelSettings {
 }
 
 impl Settings for NotificationPanelSettings {
-    type FileContent = PanelSettingsContent;
+    type FileContent = NotificationPanelSettingsContent;
 
     fn load(
         sources: SettingsSources<Self::FileContent>,