Feat: support api-key for Ollama. (#6448)

### What problem does this PR solve?

#6189

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

rag/llm/embedding_model.py

 
 class OllamaEmbed(Base):
     def __init__(self, key, model_name, **kwargs):
-        self.client = Client(host=kwargs["base_url"])
+        self.client = Client(host=kwargs["base_url"]) if not key or key == "x" else \
+            Client(host=kwargs["base_url"], headers={"Authorization": f"Bear {key}"})
         self.model_name = model_name
 
     def encode(self, texts: list):

rag/llm/tts_model.py

         self.headers = {
             "Content-Type": "application/json"
         }
+        if key and key != "x":
+            self.headers["Authorization"] = f"Bear {key}"
 
     def tts(self, text, voice="standard-voice"):
         payload = {