[HLSL] Add bool compatibility overloads

[llvm-beanz]

We have two options to consider here:

1. Observe C rules
   -or-
2. Adopt new HLSL rules as proposed in [Overload.Res] Add overload resolution sections microsoft/hlsl-specs#244

Option 1: C Rules

If we choose Option 1, this task is to add bool overloads for intrinsic where it makes sense to call them with bool values, and properly codegen those as if bool was converted to `int.

Option 2: New HLSL Rules

The spec PR posted above suggests treating bool effectively as lower than the lowest rank of integer type. A slight variation is that we could treat it as promotable to int.

[llvm-beanz]

For this change we've decided to follow C rules, so the next step here will be to audit the existing functions in HLSL.h and add appropriate boolean overloads for methods.