[clang] [clang] Merge lifetimebound and GSL code paths for lifetime analysis (PR #104906)

[Haojian Wu via cfe-commits]

hokein wrote:

> I think the PR https://github.com/llvm/llvm-project/pull/104556 should fix this.

The PRdoesn't address this issue, it appears to be a different problem. I have identified the correct solution, so my plan is as follows:

1. Reland this PR without removing EnableLifetimeWarnings (this should not cause any behavior change).
2. Then, remove EnableLifetimeWarnings with a proper fix.

https://github.com/llvm/llvm-project/pull/104906