linux: Prompt library fixes (#16850)

This PR fixes two issues:
1. The prompt library window didn't set an `app_id` on Linux, which
caused it to be missing the Zed logo
2. A dangling reference to the window in the Wayland client code, which
caused the prompt library window not to close. See:
https://github.com/zed-industries/zed/pull/13201

Release Notes:

- Linux: Fixed the prompt library not closing on Wayland

---------

Co-authored-by: Junkui Zhang <364772080@qq.com>

crates/gpui/src/platform/linux/wayland/client.rs

@@ -982,7 +982,8 @@ impl Dispatch<xdg_toplevel::XdgToplevel, ObjectId> for WaylandClientStatePtr {
         let should_close = window.handle_toplevel_event(event);
 
         if should_close {
-            this.drop_window(surface_id);
+            // The close logic will be handled in drop_window()
+            window.close();
         }
     }
 }