Feat llm http request modifier

[LylaYuKakola]

Summary

oxy.HttpLLM增加llm_request_modifier的Hook，提供在请求LLM前对headers、url、payload进行自定义修改的能力，应用在例如“headers中增加traceId来提供错误排查、payload中增加stream参数来指定流式返回”，目前应用在调用一些大模型网关的场景，适配该网关定制化的接入方式。

Related Issue(s)

• http-llm提供自定义扩展请求参数（header/payload）的钩子函数 http-llm提供自定义扩展请求参数（header/payload）的钩子函数 #21

Changes

http_llm.py中，对HttpLLM的class增加llm_request_modifier声明，提供实例化过程中的自定义扩展，在httpx.AsyncClient执行发送请求的逻辑前执行llm_request_modifier，传入headers、url、payload，处理完完整返回headers、url、payload；
对历史逻辑没有影响，在不配置llm_request_modifier的情况下，保持原本headers、url、payload的输出;

示例

def modifier_request_with_trace_id(url, headers, payload):
    headers['trace-id'] = str(uuid4())
    payload['stream'] = True
    print('---llm request---', headers['trace-id'])
    return url, headers, payload

oxy.HttpLLM(
        name="XXXXXX",
        api_key='XXXXX',
        base_url='http://XXXXXXX/v1/chat/completions',
        model_name='XXXXX',
        llm_request_modifier=modifier_request_with_trace_id,
)

Checklist

• been self-reviewed.
  • Code is formatted
  • Tests added/updated
  • All CI checks passed
  • Documentation updated
• added documentation for new or modified features or behaviors.
• added new features, such as new agents, new flows, etc.
• added or updated version, license, or notice information.
• added or updated demo, integration tests, unit tests, or others.
• added or updated ui, or had changes in frontend.