[clang] [LifetimeSafety] Add missing origins stats for lifetime analysis (PR #166568)

[Utkarsh Saxena via cfe-commits]

usx95 wrote:

> On the other hand, if we expect these to be more independent, i.e., some types are not covered and some kinds of ast nodes are not covered and there is no correlation between them, I think it might be better to collect across these two independent axises.

I agree that these are, in principle, two different parts of the problem. I am supportive of having 2 separate metrics one indexed by `StmtClass` and other by `QualType`.

https://github.com/llvm/llvm-project/pull/166568