Add BasedPyright LSP

[baco]

There is a new LSP server for Python, fork of unmaintained pyright LSP server.

The goal of this new LSP server is to also include features delegated to the closed source pylance LSP server.

[joaotavora]

This is great, great name for the new server and great idea, and I fully support the idea. pyright is somewhat poorly maintained in my opinion, and we needed this. But you know what would even be better? A PR to the README.md making it even more clear that development of Eglot does NOT take place in this repository, but rather in the Emacs upstream via bug-gnu-emacs@gnu.org. Send your patch there, please, and the Emacs maintainers will very likely install it.

[baco]

I've done it. I didn't receive any response yet.

[joaotavora]

I've done it. I didn't receive any response yet.

OK, it will eventually get some attention, I believe. In the meantime it's not like it's super hard to type M-x eglot RET basedpyright-langserver -lsp or somesuch right? Or (add-to-list eglot-server-programs as usual.