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

[Joseph Huber via llvm-commits]

jhuber6 wrote:

> I'm afraid the code style of this entire stuff will be out of control. Looking at the code, there are at least three different code styles. I don't think it's a good idea to keep as it is.

The public API and internal style can be different like with `libomp`, but it would definitely help to be consistent.

> > we can adjust as we move forward.
> 
> IMHO, most of the time with this, it roughly means, this is it, and eventually we get so many half-baked stuff.

To be fair I've deleted some of the half baked stuff in the past, but I get your point. Generally I'm less concerned overall since I've somewhat resigned myself to whatever the offload project is going to be. This one as-is can't do anything useful, but it's hard to track changes with such a big delta. We could probably make the argument that this could be opt-in or something.

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