[DirectX] Simplify errors from `RootSignatureMetadata.h`

[joaosaffran]

RootSignatureMetadata.h defines a bunch of ErrorInfo classes, we likely don't need as much as are currently defined. This task goal is to refactor and remove those error messages into a single or a handful amount of error messages. Previous discussion suggests making it similar to StringError, but with more structure.

First suggested here: #153276 (comment)