Merge httpcore2 and httpx2 into a single package?

[mgorny]

FWIU historically httpcore and httpx were developed and released somewhat separately. However, httpx2 pins to the same exact version of httpcore2, which means both packages need to be updated in tandem. Both also share the same repository. The split feels like an unnecessary churn at this point. Could you please consider merging them into a single package that would install both httpcore2 and httpx2?

[Kludex]

I think this would actually substantially increase perforamance if we merge some abstractions. 🤔