Refactor detector and model management (#23995)

* Refactor detector and model management

* Fix model resolution field

frigate/comms/dispatcher.py

@@ -261,10 +261,11 @@ class Dispatcher:
             if camera not in self.config.cameras:
                 return None
 
+            model = self.config.model_for_camera(camera)
             grid = get_camera_regions_grid(
                 camera,
                 self.config.cameras[camera].detect,
-                max(self.config.model.width, self.config.model.height),
+                max(model.width, model.height),
             )
             return grid