[HLSL] Add appropriate validation for MD_tbaa metadata kind

[bob80905]

The MD_tbaa metadata kind needs to be supported in LLVM for the DXIL Prepare pass.
Currently, if any MD_tbaa metadata kind is detected prior to the DXIL Prepare pass, it is removed thanks to the whitelist in llvm\lib\Target\DirectX\DXILPrepare.cpp under getCompatibleInstructionMDs. The whitelist needs to accomodate for MD_tbaa, and the whitelist needs extra logic to validate the MD_tbaa node in the same way that the dxil validator validates the MD_tbaa node.

[inbelic]

I poked around a bit with this. One thing worth noting is that the metadata representation of tbaa has changed substantially from DXC. Presumably, the upstream representation version is what is generated when compiling with clang.

With that noted, it raises the following implementation questions:

• When will we handle the transformation from the upstream representation to its stripped down DXC equivalent?
• And further, what version will the expected input tbaa metadata representation be when doing this validation in DXILPreparePass?

Note: DXC vs upstream llvm representations.