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/editor/src/editor.rs

@@ -129,6 +129,7 @@ use ui::{
     Tooltip,
 };
 use util::{defer, maybe, post_inc, RangeExt, ResultExt, TryFutureExt};
+use workspace::notifications::NotificationId;
 use workspace::Toast;
 use workspace::{
     searchable::SearchEvent, ItemNavHistory, SplitDirection, ViewId, Workspace, WorkspaceId,
@@ -8922,7 +8923,12 @@ impl Editor {
 
                 if let Some(workspace) = self.workspace() {
                     workspace.update(cx, |workspace, cx| {
-                        workspace.show_toast(Toast::new(0x156a5f9ee, message), cx)
+                        struct CopyPermalinkToLine;
+
+                        workspace.show_toast(
+                            Toast::new(NotificationId::unique::<CopyPermalinkToLine>(), message),
+                            cx,
+                        )
                     })
                 }
             }
@@ -8943,7 +8949,12 @@ impl Editor {
 
                 if let Some(workspace) = self.workspace() {
                     workspace.update(cx, |workspace, cx| {
-                        workspace.show_toast(Toast::new(0x45a8978, message), cx)
+                        struct OpenPermalinkToLine;
+
+                        workspace.show_toast(
+                            Toast::new(NotificationId::unique::<OpenPermalinkToLine>(), message),
+                            cx,
+                        )
                     })
                 }
             }