[llvm] [Offload] Introduce offload-tblgen and initial new API implementation (PR #108413)

[Callum Fare via llvm-commits]

callumfare wrote:


> As far as I recall, that was the preference of everyone at AMD and the only ones in favor of what we have now were Johannes and the people on the RFC that didn't contribute to `libomptarget`.

I'm not against having that discussion again, before we start actually committing new code, if it makes thing easier for us. If we keep the current approach it seems important to understand how we actually transfer the existing code (both plugins and libomptarget runtime) to the new API without breaking OpenMP things.

https://github.com/llvm/llvm-project/pull/108413