[REQ] Server stub code using FastAPI

Created by: Minyus

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

FastAPI is a Python web framework built on top of Starlette and Pydantic inspired by other frameworks explained at: https://fastapi.tiangolo.com/alternatives/

Unfortunately, OpenAPI Generator does not support to generate server stub code using FastAPI yet.

Describe the solution you'd like

Add option to generate server stub using FastAPI.