[clang] [llvm] [clang][hlsl] Add tan intrinsic part 1 (PR #90276)

[Farzon Lotfi via cfe-commits]

farzonl wrote:

> > I didn't want the current set of changes to go stale.
> 
> How many changes are we talking about here? If it's just the tan() ones, that's fine; it probably makes sense to land constrained-tan separately anyway.

There are 4 for tan. There will be more for the other intrinsics listed in the RFC. This one and three backends. There will be a 5th for arm64 after the x86 changes land.

1. https://github.com/llvm/llvm-project/pull/90276
2. https://github.com/llvm/llvm-project/pull/90277
3. https://github.com/llvm/llvm-project/pull/90278
4. https://github.com/llvm/llvm-project/pull/90503

I'll get started on landing the constrained-tan as part 6 after this change makes it.

https://github.com/llvm/llvm-project/pull/90276