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/chat_model.py

@@ -13,6 +13,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 #
+from openai.lib.azure import AzureOpenAI
 from zhipuai import ZhipuAI
 from dashscope import Generation
 from abc import ABC
@@ -94,6 +95,11 @@ class DeepSeekChat(Base):
         if not base_url: base_url="https://api.deepseek.com/v1"
         super().__init__(key, model_name, base_url)
 
+class AzureChat(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 BaiChuanChat(Base):
     def __init__(self, key, model_name="Baichuan3-Turbo", base_url="https://api.baichuan-ai.com/v1"):