file_manager: fix notification sync on fast machines

Desktop class PCs may exit the request before the inotify observer
gains control of the loop.  When the observer does gain control
it will immediately notify as the sync mutex is no longer held,
this can result in sending  the websocket notification before
the response has returned.  Delay all notifications by 5ms to prevent
this.

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

moonraker/components/file_manager/file_manager.py

@@ -2144,22 +2144,18 @@ class InotifyObserver(BaseFileSystemObserver):
                 source_root, source_path)
             result['source_item'] = {'path': src_rel_path, 'root': source_root}
         key = f"{action}-{root}-{rel_path}"
-        if sync_fut is not None:
-            # Delay this notification so that it occurs after an item
-            logging.debug(f"Syncing notification: {full_path}")
-            self.event_loop.register_callback(
-                self._sync_with_request, result, sync_fut, key
+        self.event_loop.create_task(
+            self._finish_notify(result, sync_fut, key)
         )
-        else:
-            self.file_manager.cancel_notification(key)
-            self.server.send_event("file_manager:filelist_changed", result)
 
-    async def _sync_with_request(
+    async def _finish_notify(
         self,
         result: Dict[str, Any],
-        sync_fut: asyncio.Future,
+        sync_fut: Optional[asyncio.Future],
         notify_key: str
     ) -> None:
+        if sync_fut is not None:
+            logging.debug(f"Syncing notification: {notify_key}")
             await sync_fut
         self.file_manager.cancel_notification(notify_key)
         await asyncio.sleep(.005)