Technical stuff first:

Replace existing_profiles (a dict with the filenames for both active and
inactive profiles) with active_profiles and extra_profiles which are
ProfileList()s and store the active profiles and those in the extra
directory separately. Thanks to ProfileList, now also the relation
between attachments and filenames is easily available.

Also replace all usage of existing_profiles with active_profiles and
extra_profiles, and adjust it to the ProfileList syntax everywhere.

With this change, several bugs in aa-complain and the other minitools
get fixed:
- aa-complain etc. never found profiles that have a profile name
  (the attachment wasn't checked)
- even if the profile name was given as parameter to aa-complain, it
  first did "which $parameter" so it never matched on named profiles
- profile names with alternations (without attachment specification)
  also never matched because the old code didn't use AARE.

References: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=882047#92
(search for "As usual" ;-)

Just for completeness - the matching still doesn't honor/expand
variables in the profile name.

(cherry picked from commit 4d722f18397dd35b208548d4c841b955c41ac7ce)