Special care is taken for bondethernet, where the MAC changes when
the first member is added to it. BondEthernet requires its MAC to
be set in the bondethernets section, disallowing the MAC of individual
members to be set.
Also write a dumper for MACs of all types. Update integration test
cases to stress the MAC changes on loops, bonds, and phys.
Bridges can be created with default settings, with specific settings,
and they can be sync'd at runtime with all of the settings in this
change.
Notably missing are two features:
- unknown unicast flooding into specific interfaces (as opposed to
on/off on the bridge)
- learn-limit, which does not have an API getter, only a setter.
