Implement wav2vec2 as an audio encoder model. (#9549)

This is useless on its own but there are multiple models that use it.

nodes.py

@@ -2324,6 +2324,7 @@ async def init_builtin_extra_nodes():
         "nodes_qwen.py",
         "nodes_model_patch.py",
         "nodes_easycache.py",
+        "nodes_audio_encoder.py",
     ]
 
     import_failed = []