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/feedback/src/feedback_modal.rs

@@ -17,6 +17,7 @@ use regex::Regex;
 use serde_derive::Serialize;
 use ui::{prelude::*, Button, ButtonStyle, IconPosition, Tooltip};
 use util::{http::HttpClient, ResultExt};
+use workspace::notifications::NotificationId;
 use workspace::{DismissDecision, ModalView, Toast, Workspace};
 
 use crate::{system_specs::SystemSpecs, GiveFeedback, OpenZedRepo};
@@ -127,11 +128,11 @@ impl FeedbackModal {
             let is_local_project = project.read(cx).is_local();
 
             if !is_local_project {
-                const TOAST_ID: usize = 0xdeadbeef;
+                struct FeedbackInRemoteProject;
 
                 workspace.show_toast(
                     Toast::new(
-                        TOAST_ID,
+                        NotificationId::unique::<FeedbackInRemoteProject>(),
                         "You can only submit feedback in your own project.",
                     ),
                     cx,