Simplify workspace notification code (#23414)

* Remove `NotificationHandle` trait in favor of just passing `AnyView` -
id field wasn't used.

* Remove `show_notification_once`, doesn't seem to be needed for its
only use.

Release Notes:

- N/A

crates/workspace/src/workspace.rs

@@ -47,9 +47,7 @@ use itertools::Itertools;
 use language::{LanguageRegistry, Rope};
 pub use modal_layer::*;
 use node_runtime::NodeRuntime;
-use notifications::{
-    simple_message_notification::MessageNotification, DetachAndPromptErr, NotificationHandle,
-};
+use notifications::{simple_message_notification::MessageNotification, DetachAndPromptErr};
 pub use pane::*;
 pub use pane_group::*;
 pub use persistence::{
@@ -370,7 +368,6 @@ fn prompt_and_open_paths(
 
 pub fn init(app_state: Arc<AppState>, cx: &mut AppContext) {
     init_settings(cx);
-    notifications::init(cx);
     theme_preview::init(cx);
 
     cx.on_action(Workspace::close_global);
@@ -785,7 +782,7 @@ pub struct Workspace {
     status_bar: View<StatusBar>,
     modal_layer: View<ModalLayer>,
     titlebar_item: Option<AnyView>,
-    notifications: Vec<(NotificationId, Box<dyn NotificationHandle>)>,
+    notifications: Vec<(NotificationId, AnyView)>,
     project: Model<Project>,
     follower_states: HashMap<PeerId, FollowerState>,
     last_leaders_by_pane: HashMap<WeakView<Pane>, PeerId>,
@@ -3640,7 +3637,7 @@ impl Workspace {
                     .children(
                         self.notifications
                             .iter()
-                            .map(|(_, notification)| notification.to_any()),
+                            .map(|(_, notification)| notification.clone().into_any()),
                     ),
             )
         }
@@ -4895,7 +4892,7 @@ fn notify_if_database_failed(workspace: WindowHandle<Workspace>, cx: &mut AsyncA
             if (*db::ALL_FILE_DB_FAILED).load(std::sync::atomic::Ordering::Acquire) {
                 struct DatabaseFailedNotification;
 
-                workspace.show_notification_once(
+                workspace.show_notification(
                     NotificationId::unique::<DatabaseFailedNotification>(),
                     cx,
                     |cx| {