policychecker: allow 'destination without interface' rules

policychecker: allow 'destination without interface' rules

It seems that the checking rules that require all the policy rules
with send_type="method_call" to have specified send_interface
are too strong.

This relaxes the checking rules a bit by allowing rules that:
- are in the "default" or "mandatory" contexts;
- have 'send_type' or 'receive_type set' to "method_call";
- have specified 'send_destination' or 'receive_sender'.
That is, we don't require "send_interface" or "receive interface" anymore
for such rules.

Change-Id: Iefa9bb5a5e23319c7549fa597ab00b5c88600585