[clang] [clang][Sema] Fix the continue and break scope for while loops (PR #152606)

[via cfe-commits]

Sirraide wrote:

I was going to implement this approach as part of my named loops implementation, but adding a scope flag requires to change the underlying type to a uint64_t (because we already have 32 scope flags at the moment), so I thought it’d be better to make that a separate patch.

https://github.com/llvm/llvm-project/pull/152606