[HLSL] CodeGen hlsl resource binding.

''register(ID, space)'' like register(t3, space1) will be translated into
i32 3, i32 1 as the last 2 operands for resource annotation metadata.

NamedMetadata for CBuffers and SRVs are added as "hlsl.srvs" and "hlsl.cbufs".

Reviewed By: beanz

Differential Revision: https://reviews.llvm.org/D130951