Integrates LLM Azure OpenAI (#1318)

### What problem does this PR solve?

feat: Integrates LLM Azure OpenAI #716 

### Type of change

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

### Other
It's just the back-end code, the front-end needs to provide the Azure
OpenAI model addition form.
   
#### Required parameters

- base_url
- api_key

---------

Co-authored-by: yonghui li <yonghui.li@bondex.com.cn>

rag/llm/embedding_model.py

@@ -18,6 +18,7 @@ from typing import Optional
 import  threading
 import requests
 from huggingface_hub import snapshot_download
+from openai.lib.azure import AzureOpenAI
 from zhipuai import ZhipuAI
 import os
 from abc import ABC
@@ -110,6 +111,11 @@ class OpenAIEmbed(Base):
         return np.array(res.data[0].embedding), res.usage.total_tokens
 
 
+class AzureEmbed(Base):
+    def __init__(self, key, model_name, **kwargs):
+        self.client = AzureOpenAI(api_key=key, azure_endpoint=kwargs["base_url"], api_version="2024-02-01")
+        self.model_name = model_name
+
 class BaiChuanEmbed(OpenAIEmbed):
     def __init__(self, key,
                  model_name='Baichuan-Text-Embedding',