Fix dkms installation of deb packages created with Alien.

Alien does not honour the %posttrans hook.
So move the dkms uninstall/install scripts to the
%pre/%post hooks in case of package install/upgrade.
In case of package removal, handle that in %preun.
Add removal of all old dkms modules.
Add checking for broken 'dkms status'. Handle that as
good as possible and warn the user about it.
Also add more verbose messages about what we are doing.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Mart Frauenlob <AllKind@fastest.cc>
Closes #15415