[clang] [Liveness][analyzer] Fix handling of [[assume]] attributes (PR #198618)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

I adjusted this PR by using the name 'StackFrame' instead of 'LocationContext' (because https://github.com/llvm/llvm-project/pull/198211 was merged recently). As this is a completely mechanical change, I'm merging this without further review.

https://github.com/llvm/llvm-project/pull/198618