Rework os-release and issue mechanism
Avoids upgrade issues such as competing fedora-release-$EDITION packages
Makes a non-product install persistent (it won't be converted to an Edition
install if something pulls in a fedora-release-$EDITION package
Known issues: Right now, the RPM transaction solver always installs the
fedora-release-$EDITION packages immediately after the fedora-release
package, but it's unsafe to assume this. If this logic ever changes,
there might be a gap for initial installation from anaconda where packages
installed between fedora-release and fedora-release-$EDITION might end up
with non-product defaults instead of productized ones. This is no
different from the behavior prior to this patch, but it is not fixed by
this patch. However, this problem was also previously vulnerable on
upgrades, which will not be after this patch.