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/data_processing/common/license_plate/mixin.py

@@ -1054,13 +1054,19 @@ class LicensePlateProcessingMixin:
                     for plate in plates
                 )
             ),
-            top_plate,
+            None,
         )
 
-        # Send the result to the API
+        # If it's a known plate, publish to sub_label
+        if sub_label is not None:
+            self.sub_label_publisher.publish(
+                EventMetadataTypeEnum.sub_label, (id, sub_label, avg_confidence)
+            )
+
         self.sub_label_publisher.publish(
-            EventMetadataTypeEnum.sub_label, (id, sub_label, avg_confidence)
+            EventMetadataTypeEnum.identifier, (id, top_plate, avg_confidence)
         )
+
         self.detected_license_plates[id] = {
             "plate": top_plate,
             "char_confidences": top_char_confidences,