[clang][analyzer] Print empty per-EP metrics as empty CSV cells, fix missing PathRunningTime metric (#162839)

To avoid information loss, introduce a difference between unset stats
and 0 for statistics that are supposed to be set once per entry point.
Now, if the statistic is not set for an entry point, the corresponding
CSV cell will be empty, and not 0.

Thanks to this differentiation, I noticed that `PathRunningTime` was
actually never set, and fixed that.
Additionally, this patch enables the timers if
`DumpEntryPointStatsToCSV` is set, because in most cases you dump these
stats to get a detailed view on analyzer performance.

Finally, I added a dedicated debug checker that demonstrates the use of
a statistic and tested the set and unset scenarios explicitly.

--

CPP-7097

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Co-authored-by: Donát Nagy <donat.nagy@ericsson.com>

0 files changed, 0 insertions, 0 deletions