[openmp] [clang] [llvm] [OpenMP] Introduce support for OMPX extensions and taskgraph frontend (PR #66919)

[Alexey Bataev via cfe-commits]

alexey-bataev wrote:

> Sorry, @alexey-bataev, some were marked as resolved, and we did not see them.
> 
> The wording on my previous question needed to be corrected, too. I did not mean to ask if this is ready to land as is but instead if the division of the original PR into just this front-end part is what you would suggest we do.

Yes, this is what suggest

https://github.com/llvm/llvm-project/pull/66919