[REQ] [python-fastapi] change src folder in python-fastapi generator

Created by: rk0n

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

The FastAPI generator template generates a openapi_server package in folder src and leads to src/openapi_server as path. The src part of the path cannot be changed although there is a constant in the python-fastapi codegen script

Describe the solution you'd like

Use a variable in python-fastapi.yaml file (e.g.: sourceFolder) variable to define the path of the generated openapi_server code So that the openapi_server package can be generated to src/apis/openapi_server or openapi_server for example.

Describe alternatives you've considered

Tried to change this by template

Additional context

Could deliver code for this feature and open to discuss about it