[HLSL] Add WaveActiveCountBits as Langugage builtin function for HLSL

One clang builtins are introduced
 uint WaveActiveCountBits( bool bBit ) as Langugage builtin function for HLSL.

The detail for WaveActiveCountBits is at
https://github.com/microsoft/DirectXShaderCompiler/wiki/Wave-Intrinsics#uint-waveactivecountbits-bool-bbit-

This is only clang part change to make WaveActiveCountBits into AST.
llvm intrinsic for WaveActiveCountBits will be add in separate PR.

Reviewed By: Anastasia

Differential Revision: https://reviews.llvm.org/D126857