Refactor workspace notifications to use explicit NotificationId type (#10342)

This PR reworks the way workspace notifications are identified to use a
new `NotificationId` type.

A `NotificationId` is bound to a given type that is used as a unique
identifier. Generally this will be a unit struct that can be used to
uniquely identify this notification.

A `NotificationId` can also accept an optional `ElementId` in order to
distinguish between different notifications of the same type.

This system avoids the issue we had previously of selecting `usize` IDs
somewhat arbitrarily and running the risk of having two independent
notifications collide (and thus interfere with each other).

This also fixes a bug where multiple suggestion notifications for the
same extension could be live at once

Fixes https://github.com/zed-industries/zed/issues/10320.

Release Notes:

- Fixed a bug where multiple extension suggestions for the same
extension could be shown at once
([#10320](https://github.com/zed-industries/zed/issues/10320)).

---------

Co-authored-by: Max <max@zed.dev>

crates/extensions_ui/src/extension_suggest.rs

@@ -5,9 +5,10 @@ use std::sync::{Arc, OnceLock};
 use db::kvp::KEY_VALUE_STORE;
 use editor::Editor;
 use extension::ExtensionStore;
-use gpui::{Entity, Model, VisualContext};
+use gpui::{Model, VisualContext};
 use language::Buffer;
-use ui::ViewContext;
+use ui::{SharedString, ViewContext};
+use workspace::notifications::NotificationId;
 use workspace::{notifications::simple_message_notification, Workspace};
 
 fn suggested_extensions() -> &'static HashMap<&'static str, Arc<str>> {
@@ -140,7 +141,13 @@ pub(crate) fn suggest(buffer: Model<Buffer>, cx: &mut ViewContext<Workspace>) {
             return;
         }
 
-        workspace.show_notification(buffer.entity_id().as_u64() as usize, cx, |cx| {
+        struct ExtensionSuggestionNotification;
+
+        let notification_id = NotificationId::identified::<ExtensionSuggestionNotification>(
+            SharedString::from(extension_id.clone()),
+        );
+
+        workspace.show_notification(notification_id, cx, |cx| {
             cx.new_view(move |_cx| {
                 simple_message_notification::MessageNotification::new(format!(
                     "Do you want to install the recommended '{}' extension for '{}' files?",