[HLSL] implement `clamp` intrinsic (#85424)

closes #70071
- `CGBuiltin.cpp` - Add the unsigned\generic clamp intrinsic emitter.
- `IntrinsicsDirectX.td` - add the `dx.clamp` & `dx.uclamp` intrinsics
- `DXILIntrinsicExpansion.cpp` - add the `clamp` instruction expansion
while maintaining vector form.
- `SemaChecking.cpp` -  Add `clamp`  builtin Sema Checks.
- `Builtins.td` - add a `clamp` builtin
- `hlsl_intrinsics.h` - add the `clamp` api

Why `clamp` as instruction expansion  for DXIL?
1. SPIR-V has a GLSL `clamp` extension via:
-
[FClamp](https://registry.khronos.org/SPIR-V/specs/1.0/GLSL.std.450.html#FClamp)
-
[UClamp](https://registry.khronos.org/SPIR-V/specs/1.0/GLSL.std.450.html#UClamp)
-
[SClamp](https://registry.khronos.org/SPIR-V/specs/1.0/GLSL.std.450.html#SClamp)
2. Further Clamp lowers to `min(max( x, min_range ), max_range)` which
we have float, signed, & unsigned dixilOps.