Add CMake build system

[ProExpertProg]

Added a CMake-based build system to enable building this package from source in the vLLM build. That will allow using PyTorch nightly, which is needed by the torch.compile and another project in vLLM.

Heavily inspired by the new build system in vLLM.

[bnellnm]

LGTM. Just one minor comment in the test file.

[bnellnm]

Sorry, I missed the python finding code first time.

[ProExpertProg]

(marking as draft until I resolve the binary size/arch explosion)