fwget: add -q for quiet output

Introduce -q to quieten other output (unless -v is also given).

pkg-install(8) currently has no option to allow skipping unavail
packages but it will just fail.
We would realy want to try to install as much firmware found as
possible from the installer.
Work around this by doing one firmware package at a time.
For that it is highly helpful to be able to query (or possibly re-query)
all outstanding fimrware packages.
-q together with -n only shows each package to be installed one by line.

Once https://github.com/freebsd/pkg/issues/2195 will be implemented
we could undo this part of the change and future changes to the installer
and use the new option for pkg-install(8) there.

While here switch to getopts so -qn works and not just -q -n.

Sponsored by: The FreeBSD Foundation
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D47445