[llvm] [DXIL] Adding support to RootSignatureFlags generation to DXContainer (PR #122396)

[Chris B via llvm-commits]

https://github.com/llvm-beanz commented:

In the past when we've made changes to support emitting new parts of the container file we've broken the changes up into multiple PRs that land separately. Usually the first PR adds parsing and YAML tooling (with YAML roundtrip tests), and the second PR adds support for generating the data from IR and emitting the final file.

I believe this PR would benefit from being split up that way to make it easier to review.

https://github.com/llvm/llvm-project/pull/122396