[clang] [llvm] [NFC][HLSL][DXIL] Move D3D12.h enums and flags to DXILABI (PR #143041)

[Justin Bogner via llvm-commits]

https://github.com/bogner approved this pull request.

This makes sense to me. As a follow up, we should look into whether BinaryFormat/DXContainer.h can get some of these enum values from here rather than duplicating their values.

https://github.com/llvm/llvm-project/pull/143041