[clang] [AST] Assert that FoldingSetNodeID used for hint is correct upon insertion (PR #157692)

[Ilya Biryukov via cfe-commits]

ilya-biryukov wrote:

Sharing this early to showcase the approach and see if folks are on board with that.
The approach adds some boilerplate and requires discipline, but I couldn't come up with a different one that avoids that.

I have seen some failures (~150) with `ninja check-clang`, will investigate and fix before sending this out for a proper review.

https://github.com/llvm/llvm-project/pull/157692