git-unpack-objects: show progress report by default

git-unpack-objects: show progress report by default

This ends up being very calming for big "git clone"s, since otherwise
you just get very frustrated with a long silence, wondering whether it's
working at all.

Use "-q" to quiet it down.

Now if we could just do the same for the initial "figure out what to
pack" phase, which can also be quite slow if the other end is busy (or
not packed and not in cache)...