proposal: generate API docs for API server

[welkeyever]

Is your feature request related to a problem? Please describe.

No

Describe the solution you'd like

Generate api docs for api server(hertz/kitex), maybe integrating protoc/thrift plugin during the generation phase.

Describe alternatives you've considered

Hertz may cooperate with swagger middleware. Kitex not sure for now...

Additional context

[FGYFFFF]

The thrift/protoc plug-in implementation is the most ideal. The protobuf plugin is currently available, thrift is not.

Middleware is also possible, but requires kitex support for a swagger middleware

[li-jin-gou]

There are real user requirements that exist for thrift to generate swagger. cc @chaoranz758