[REQ] Drogon server generation support.

[Rz-Rz]

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

I have been needing to use the server generation feature/description of openapi with the c++ http webserver drogon. Currently I have no been able to find any such implementation.

Describe the solution you'd like

I have been currently implement the server generation feature. I am wondering about the specifics to get it implemented. We have no need of the XML feature and have been wanting to ignore it. Is it still possible to ask for a pull request, if the xml features are missing ?

Describe alternatives you've considered

I can write the openapi and write the server code side by side, but it's time consuming.

Additional context

We have been making good progress and should finish by the end of summer.

[wing328]

@Rz-Rz thanks for contributing a new generator. Let us know if you need any help

Recently, we merged one related to new C++ server codegen: #21547