progress: hide progress bar when --quiet

We want progress bars in the default output mode, but not when the
user specifies --quiet.  Add a setting to the Progress bar class so
it takes care of not displaying anything itself rather than having
to update every subcommand to conditionally setup & call the object.

Change-Id: I1134993bffc5437bc22e26be11a512125f10597f
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/303225


Reviewed-by: Raman Tenneti <rtenneti@google.com>
Tested-by: Mike Frysinger <vapier@google.com>