apparmor: rework profile->rules to be a list

apparmor: rework profile->rules to be a list

Convert profile->rules to a list as the next step towards supporting
multiple rulesets in a profile. For this step only support a single
list entry item. The logic for iterating the list will come as a
separate step.

Signed-off-by: John Johansen <john.johansen@canonical.com>