add additional verbosity options

[grosser]

replaces #694

--verbose currently displays both the command to be executed by each parallel
process before the tests run, and, on failure of a process, the command
needed to rerun the failing process.

We prefer to display only the latter.

This patch adds flags that can be used instead of --verbose to enable
either the per-process command, or the rerun command, or both.

--verbose-process-command will show the per-process commands, even if
--verbose is not set, or --quiet is set.

--verbose-rerun-command will show the rerun command, even if --verbose
is not set, or --quiet is set.

If --verbose is set, both types of command will be displayed, regardless
of whether the flags for those commands are set or not.

@alboyadjian

[grosser]

@alboyadjian I bet quiet/verbose/verbose-flavors could use some rework too ... like quiet suppressing non-verbose output so that uses can use quiet and verbose together and we can remove the warning ... but good enough for now ...

[alboyadjian]

This will totally do what we need to do and the tests are cleaner. Thank you.

Thanks very much for creating (and maintaining) this tool, as well as the many others that I have used over the years.

[grosser]

v2.29.0