[HLSL] Add resource binding attribute for HLSL.

[HLSL] Add resource binding attribute for HLSL.

The resource binding attribute is to set the virtual registers and logical register spaces resources in HLSL are bound to.
Format is ''register(ID,  space)'' like register(t3,  space1).
ID must be start with
t – for shader resource views (SRV),
s – for samplers,
u – for unordered access views (UAV),
b – for constant buffer views (CBV).

Register space is default to space0.

The full documentation is available here: https://docs.microsoft.com/en-us/windows/win32/direct3d12/resource-binding-in-hlsl

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D130033