Refactor processors and add LPR postprocessing (#16722)

* recordings data pub/sub

* function to process recording stream frames

* model runner

* lpr model runner

* refactor to mixin class and use model runner

* separate out realtime and post processors

* move model and mixin folders

* basic postprocessor

* clean up

* docs

* postprocessing logic

* clean up

* return none if recordings are disabled

* run postprocessor handle_requests too

* tweak expansion

* add put endpoint

* postprocessor tweaks with endpoint

frigate/comms/embeddings_updater.py

@@ -15,6 +15,7 @@ class EmbeddingsRequestEnum(Enum):
     generate_search = "generate_search"
     register_face = "register_face"
     reprocess_face = "reprocess_face"
+    reprocess_plate = "reprocess_plate"
 
 
 class EmbeddingsResponder:

frigate/comms/recordings_updater.py

@@ -0,0 +1,36 @@
+"""Facilitates communication between processes."""
+
+import logging
+from enum import Enum
+
+from .zmq_proxy import Publisher, Subscriber
+
+logger = logging.getLogger(__name__)
+
+
+class RecordingsDataTypeEnum(str, Enum):
+    all = ""
+    recordings_available_through = "recordings_available_through"
+
+
+class RecordingsDataPublisher(Publisher):
+    """Publishes latest recording data."""
+
+    topic_base = "recordings/"
+
+    def __init__(self, topic: RecordingsDataTypeEnum) -> None:
+        topic = topic.value
+        super().__init__(topic)
+
+    def publish(self, payload: tuple[str, float]) -> None:
+        super().publish(payload)
+
+
+class RecordingsDataSubscriber(Subscriber):
+    """Receives latest recording data."""
+
+    topic_base = "recordings/"
+
+    def __init__(self, topic: RecordingsDataTypeEnum) -> None:
+        topic = topic.value
+        super().__init__(topic)