Option to auto-close deleted files with no unsaved edits (#31920)

Closes #27982

Release Notes:

- Added `close_on_file_delete` setting (off by default) to allow closing
open files after they have been deleted on disk

---------

Co-authored-by: Bennet Bo Fenner <bennetbo@gmx.de>

crates/workspace/src/workspace_settings.rs

@@ -26,6 +26,7 @@ pub struct WorkspaceSettings {
     pub max_tabs: Option<NonZeroUsize>,
     pub when_closing_with_no_tabs: CloseWindowWhenNoItems,
     pub on_last_window_closed: OnLastWindowClosed,
+    pub close_on_file_delete: bool,
 }
 
 #[derive(Copy, Clone, Default, Serialize, Deserialize, JsonSchema)]
@@ -197,6 +198,10 @@ pub struct WorkspaceSettingsContent {
     ///
     /// Default: auto (nothing on macOS, "app quit" otherwise)
     pub on_last_window_closed: Option<OnLastWindowClosed>,
+    /// Whether to automatically close files that have been deleted on disk.
+    ///
+    /// Default: false
+    pub close_on_file_delete: Option<bool>,
 }
 
 #[derive(Deserialize)]