[clang] [analyzer] Add metrics tracking time spent in Z3 solver (PR #133236)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat approved this pull request.

LGTM.

I'm a bit surprised to see that you're excluding the retries from this measurement (I feel that measuring the total time would be a more "natural" statistic), but if you're interested in this information, then there is no reason to oppose measuring it.

https://github.com/llvm/llvm-project/pull/133236