[clang] [clang][CUDA] Add 'noconvergent' function and statement attribute (PR #100637)

[Sameer Sahasrabuddhe via cfe-commits]

ssahasra wrote:

> > Please also update the documentation for the attribute and the release notes.
> 
> It looks like you may have overlooked the request to add release notes for this new feature.

@darkbuck, please revert and address the documentation!

https://github.com/llvm/llvm-project/pull/100637