Doesn't support `sync/async` generation python client. Something like httpx

[ArtemIsmagilov]

I want to be able to generate a client that supports both synchronous and asynchronous interfaces in Python.
You can use the httpx client for this, which supports both blocking and non-blocking clients.
At the moment you only support asyncio or urllib3.

[wing328]

@ArtemIsmagilov we welcome PR to add httpx support. Would you like to contribute a PR for that?

[QBH3]

@wing328 i am very much in favour of implementing this, where should i start to look in the generator to implement httpx as a client library? /cc @thoumasd

[mas-chen]

Is it possible for the sync client to use httpx as well?