MAJOR: acl: make acl_find_targets also resolve proxy names at config time

MAJOR: acl: make acl_find_targets also resolve proxy names at config time

Proxy names are now resolved when the config is parsed and not at runtime.
This means that errors will be caught for real instead of having an ACL
silently never match. Another benefit is that the fetch will be much faster
since the lookup will not have to be performed anymore, eg for all ACLs
based on explicitly named stick-tables.

However some buggy configurations which used to silently fail in the past
will now refuse to load, hence the MAJOR tag.