[clang] [llvm] [HLSL][RootSignature] Implement Parsing of Descriptor Tables (PR #122982)

[Finn Plummer via cfe-commits]

inbelic wrote:

Please ignore the first commit. It is a duplicate of https://github.com/llvm/llvm-project/pull/122981

https://github.com/llvm/llvm-project/pull/122982