[clang] [APINotes] Diagnose invalid Where.Parameters selectors (PR #209408)

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StoeckOverflow wrote:

Thanks for the feedback, updated this to follow the suggested `DenseMap<APINotesFunctionSelectorKey, bool>` shape.

The diagnostic state now tracks exact selector keys directly, with the bool recording whether Sema matched that selector. I removed the extra `APINotesFunctionSelector` / diagnostic-entry representation entirely, so parameter spellings are no longer stored in Sema state. They are reconstructed lazily through the reader only when emitting an unmatched-selector warning.

https://github.com/llvm/llvm-project/pull/209408