Feat: implement novitaAI embedding and reranking. (#8250)

### What problem does this PR solve?

Close #8227

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

rag/llm/embedding_model.py

@@ -913,3 +913,8 @@ class GPUStackEmbed(OpenAIEmbed):
 
         self.client = OpenAI(api_key=key, base_url=base_url)
         self.model_name = model_name
+
+
+class NovitaEmbed(SILICONFLOWEmbed):
+    def __init__(self, key, model_name, base_url="https://api.novita.ai/v3/openai/embeddings"):
+        super().__init__(key, model_name, base_url)