[clang] [Clang] add emit -Wignored-base-class-qualifiers diagnostic for cv-qualified base classes (PR #132116)

[Lyle Dean via cfe-commits]

lyledean1 wrote:

Happy to adjust this @MagentaTreehouse for LLVM 20 - what would that require?

@erichkeane is this ok to merge (assuming I make the changes for the above - the CI has passed)

https://github.com/llvm/llvm-project/pull/132116