Update http_trigger to add settings for media_type and headers for no…

[quqibing]

…n-streaming responses.

[Aries-ckt]

thanks for your pr! @fangyinc

[fangyinc]

@quqibing Thans for your PR. But after my testing, I found that the example codes does not work properly. My idea here is to return the result directly and let fastapi automatically recognize it, of course, if you have a better solution, we are very welcome.