[clang] [StrTable] Mechanically convert NVPTX builtins to use TableGen (PR #122873)

[Chandler Carruth via cfe-commits]

chandlerc wrote:

Ping!

I've updated this to incorporate the changes in #123398 to the NVPTX.def file this is replacing.

Adding the author & reviewers of that PR to this -- I'd really like to either get this landed or figure out what other approach to use it avoid having to continually update this to reflect more changes. =]

https://github.com/llvm/llvm-project/pull/122873