Add 'zfs-qemu-packages' workflow for RPM building

Add a new 'zfs-qemu-packages' GH workflow for manually building RPMs
and test installing ZFS RPMs from a yum repo. The workflow has a
dropdown menu in the Github runners tab with two options:

Build RPMs - Build release RPMs and tarballs and put them into an

artifact ZIP file.  The directory structure used in
the ZIP file mirrors the ZFS yum repo.

Test repo - Test install the ZFS RPMs from the ZFS repo. On

Almalinux, this will do a DKMS and KMOD test install
from both the regular and testing repos.  On Fedora,
it will do a DKMS install from the regular repo.  All
test install results will be displayed in the Github
runner Summary page. Note that the workflow provides an
optional text box where you can specify the full URL to
an alternate repo.  If left blank, it will install from
the default repo from the zfs-release RPM.

Most developers will never need to use this workflow. It is intended
to be used by the ZFS admins for building and testing releases.

This commit also modularizes many of the runner scripts so they can
be used by both the zfs-qemu and zfs-qemu-packages workflows.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #17005