Add a command to dump profiling output.

There's a few reasons this is useful:

1. Puts profile dumping into the same group of commands as the ones that start and stop the profiler.
2. None of the vprof_generate_report commands do a FULL dump, that is, a dump that includes the hierarchy output as well as outputs sorted by time, average time, and peak time. Without this you'd need to run multiple vprof_generate_report commands in order to get this entire output.