apt: allow specifying dpkg options

This will allow specifying dpkg options as a string passed over to apt
command. dpkg_options expects a properly formatted string and defaults
to '-o "Dpkg::Options::=--force-confdef" -o
"Dpkg::Options::=--force-confold"'
Example usage would be:
-m apt -u ubuntu -s -a "upgrade=dist update_cache=yes dpkg_options='-o
\"Dpkg::Options::=--force-confold\"'"
or
apt: upgrade=dist update_cache=yes dpkg_options='-o
\"Dpkg::Options::=--force-confold\"'