feat(model): Add new LLMClient and new build tools (#967)

examples/sdk/simple_sdk_llm_example.py

@@ -1,13 +1,19 @@
 import asyncio
 from dbgpt.core.awel import DAG
-from dbgpt.core import BaseOutputParser, OpenAILLM, RequestBuildOperator, PromptTemplate
+from dbgpt.core import (
+    BaseOutputParser,
+    RequestBuildOperator,
+    PromptTemplate,
+    LLMOperator,
+)
+from dbgpt.model import OpenAILLMClient
 
 with DAG("simple_sdk_llm_example_dag") as dag:
     prompt_task = PromptTemplate.from_template(
         "Write a SQL of {dialect} to query all data of {table_name}."
     )
     model_pre_handle_task = RequestBuildOperator(model="gpt-3.5-turbo")
-    llm_task = OpenAILLM()
+    llm_task = LLMOperator(OpenAILLMClient())
     out_parse_task = BaseOutputParser()
     prompt_task >> model_pre_handle_task >> llm_task >> out_parse_task