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

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

I think having to call a separate thing at every use site is a bit prone to error. Can't we just check this at `InsertNode` instead?

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