Revise the MessageNotification component (#24287)

This PR makes adding icons to the primary and secondary actions, in the
`MessageNotification` component, optional. Also took the opportunity to
remove a probably unnecessary "third action" from it; streamlining the
component API (we had added that for a design that we're not using
anymore). I did keep the "more info" possibility, which may be useful in
the future, though.

Release Notes:

- N/A

crates/workspace/src/workspace.rs

@@ -5207,8 +5207,9 @@ fn notify_if_database_failed(workspace: WindowHandle<Workspace>, cx: &mut AsyncA
                     |cx| {
                         cx.new(|_| {
                             MessageNotification::new("Failed to load the database file.")
-                                .with_click_message("File an issue")
-                                .on_click(|_window, cx| cx.open_url(REPORT_ISSUE_URL))
+                                .primary_message("File an Issue")
+                                .primary_icon(IconName::Plus)
+                                .primary_on_click(|_window, cx| cx.open_url(REPORT_ISSUE_URL))
                         })
                     },
                 );