Could we get a command-line option for setting `kPidAndTidLabels`?

[mhansen]

Would love to be able to get per-thread tags in the output, using this constant:

perf_data_converter/src/perf_data_converter.h

Line 32 in e8a6590

kPidAndTidLabels = 3,

perf_to_profile could take a command line argument for this?

[mhansen]

I find this particularly useful for zooming in on relevant threads when doing a whole-system or a multithreaded app analysis.