[clang] [CIR] Add math and builtin intrinsics support (PR #175233)

[Hendrik Hübner via cfe-commits]

HendrikHuebner wrote:

@adams381 You still have not broken this up into smaller PRs. I don't feel confident about merging a 3000 line diff. It's hard to review this much code at once and it seems to me that AI might have been involved in its creation. This is [not necessarily a problem](https://llvm.org/docs/AIToolPolicy.html) but it makes thorough reviews even more important.

https://github.com/llvm/llvm-project/pull/175233