[clang] [clang] Implement instantiation context note for checking template parameters (PR #126088)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

@nikic thanks for the report, I missed your message, only saw when Corentin pinged.

Are you sure that's correct? I had run this patch through llvm-time-tracker before merging, and it had shown practically no impact.

Here: https://llvm-compile-time-tracker.com/compare.php?from=4eab2194872d54e2d4496135a277b1610ff33ead&to=adde9f1f8eabe4d98ba09fd978f8d152a9865347&stat=instructions:u

https://github.com/llvm/llvm-project/pull/126088