Audio transcription support (#18398)

* install new packages for transcription support

* add config options

* audio maintainer modifications to support transcription

* pass main config to audio process

* embeddings support

* api and transcription post processor

* embeddings maintainer support for post processor

* live audio transcription with sherpa and faster-whisper

* update dispatcher with live transcription topic

* frontend websocket

* frontend live transcription

* frontend changes for speech events

* i18n changes

* docs

* mqtt docs

* fix linter

* use float16 and small model on gpu for real-time

* fix return value and use requestor to embed description instead of passing embeddings

* run real-time transcription in its own thread

* tweaks

* publish live transcriptions on their own topic instead of tracked_object_update

* config validator and docs

* clarify docs

frigate/embeddings/__init__.py

@@ -300,3 +300,8 @@ class EmbeddingsContext:
 
     def reindex_embeddings(self) -> dict[str, Any]:
         return self.requestor.send_data(EmbeddingsRequestEnum.reindex.value, {})
+
+    def transcribe_audio(self, event: dict[str, any]) -> dict[str, any]:
+        return self.requestor.send_data(
+            EmbeddingsRequestEnum.transcribe_audio.value, {"event": event}
+        )