[clang] [clang] Avoid crash due to unimplemented StructuralValue support in the template differ (PR #93265)

[Andrey Ali Khan Bolshakov via cfe-commits]

https://github.com/bolshakov-a approved this pull request.

One question about the version of the C++ standard under testing, otherwise LGTM, thanks!

https://github.com/llvm/llvm-project/pull/93265