In some cases we need to just mount /proc and /dev so this moves the
mount and cleanup code for that into ProcMount, leaving the dracut
specific code in DracutChroot (which uses ProcMount).

Some packages expect a filesystem that looks more like a real system. So
this mounts /proc and /dev inside the dnf installroot while packages are
being installed.

This was prompted by a systemd change which has been fixed
(systemd/systemd#28388) but as noted, it may
happen again.

Also update tests to adjust for this. Sadly the run_pkg_transaction test
can now only be run as root. And when it doesn't run there is no /etc in
the installroot so make the directory just to be sure it is present.

Macintosh HFS changed to Apple HFS. Accept either one.

--releasever=/ isn't setting $releasever when using dnf5.

The new pylint/astroid on rawhide doesn't know how to deal with
datetime. Ignore the false positive error until it is fixed.