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

This change is an implementation of #87367's investigation on supporting
IEEE math operations as intrinsics.
Which was discussed in this RFC:
https://discourse.llvm.org/t/rfc-all-the-math-intrinsics/78294

If you want an overarching view of how this will all connect see:
https://github.com/llvm/llvm-project/pull/90088

Changes:
- `clang/docs/LanguageExtensions.rst` - Document the new elementwise tan
builtin.
-  `clang/include/clang/Basic/Builtins.td` - Implement the tan builtin.
- `clang/lib/CodeGen/CGBuiltin.cpp` - invoke the tan intrinsic on uses
of the builtin
- `clang/lib/Headers/hlsl/hlsl_intrinsics.h` - Associate the tan builtin
with the equivalent hlsl apis
- `clang/lib/Sema/SemaChecking.cpp` - Add generic sema checks as well as
HLSL specifc sema checks to the tan builtin
-  `llvm/include/llvm/IR/Intrinsics.td` - Create the tan intrinsic
-  `llvm/docs/LangRef.rst` - Document the tan intrinsic