[llvm] [lldb] [mlir] [libc] [libcxx] [openmp] [libunwind] [clang-tools-extra] [flang] [libcxxabi] [lld] [clang] [Clang][Sema] Don't say "is declared here" for invalid template locations (PR #71264)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman approved this pull request.

I like the behavior of this and the changes LGTM, but please give @ErichKeane a chance to weigh in as templates code owner before landing.

https://github.com/llvm/llvm-project/pull/71264