profiles: Add a hosts abstraction

host files can reference other files, from man 5 hosts.allow

A string that begins with a '/' character is treated as a file name. A host name or address is matched if it matches any host name or address pattern listed in the named file. The file format is zero or more lines with zero or more host name or address patterns separated by whitespace. A file name pattern can be used anywhere a host name or address pattern can be used.

This means adding a file to hosts requires updating multiple profiles Add a hosts abstraction so users only have to modify a single location.

Fixes: https://bugs.launchpad.net/ubuntu/+source/apparmor/+bug/1864466 Signed-off-by: John Johansen john.johansen@canonical.com