Use identifier field for unknown license plates (#17123)

* backend

* backend fixes

* api for search queries

* frontend

* docs

* add filterable scroll list to more filters pane for identifiers

* always publish identifier

frigate/track/tracked_object.py

@@ -153,6 +153,8 @@ class TrackedObject:
                     "current_estimated_speed": self.current_estimated_speed,
                     "velocity_angle": self.velocity_angle,
                     "path_data": self.path_data,
+                    "identifier": obj_data.get("identifier"),
+                    "identifier_score": obj_data.get("identifier_score"),
                 }
                 thumb_update = True
 
@@ -365,6 +367,7 @@ class TrackedObject:
             "average_estimated_speed": self.average_estimated_speed,
             "velocity_angle": self.velocity_angle,
             "path_data": self.path_data,
+            "identifier": self.obj_data.get("identifier"),
         }
 
         return event