Add user-visible output for remote operations (#25849)

This PR adds toasts for reporting success and errors from remote git
operations. This PR also adds a focus handle to notifications, in
anticipation of making them keyboard accessible.

Release Notes:

- N/A

---------

Co-authored-by: julia <julia@zed.dev>

crates/workspace/src/modal_layer.rs

@@ -112,7 +112,7 @@ impl ModalLayer {
         cx.notify();
     }
 
-    fn hide_modal(&mut self, window: &mut Window, cx: &mut Context<Self>) -> bool {
+    pub fn hide_modal(&mut self, window: &mut Window, cx: &mut Context<Self>) -> bool {
         let Some(active_modal) = self.active_modal.as_mut() else {
             self.dismiss_on_focus_lost = false;
             return false;