[clang] [clang] Emit -Wdangling diagnoses for cases where a gsl-pointer is construct from a gsl-owner object in a container. (PR #104556)

[Haojian Wu via cfe-commits]

hokein wrote:

I've refined the PR, and the new implementation eliminates the false positive mentioned above (I've also added a few more tests to verify this). Please take a look. The changes include some refactoring (I'm happy to split those out if they make the review process harder).

https://github.com/llvm/llvm-project/pull/104556