Add a way to clear activity indicator (#30156)

Follow-up of https://github.com/zed-industries/zed/pull/30015

* Restyles the dismiss and close buttons a bit: change the dismiss icon
and add tooltips with the bindings to both
* Allows ESC to clear any status that's in the activity indicator now,
if all notifications are cleared: this won't suppress any further status
additions though, so statuses may resurface later

Release Notes:

- Added a way to clear activity indicator

crates/auto_update/src/auto_update.rs

@@ -335,9 +335,13 @@ impl AutoUpdater {
         self.status.clone()
     }
 
-    pub fn dismiss_error(&mut self, cx: &mut Context<Self>) {
+    pub fn dismiss_error(&mut self, cx: &mut Context<Self>) -> bool {
+        if self.status == AutoUpdateStatus::Idle {
+            return false;
+        }
         self.status = AutoUpdateStatus::Idle;
         cx.notify();
+        true
     }
 
     // If you are packaging Zed and need to override the place it downloads SSH remotes from,