This requires a schema change, adding 'mode' and 'load-balance' fields,
a semantic invariant that 'load-balance' can only be set in the case of
LACP and XOR bonds, a mapper from the mode/lb strings, ie.
"round-robin" to their VPP numeric counterparts, a bunch of unit tests.
Then in the reconciler, changing bonds (__bond_has_diff()) will
invalidate any LCP or sub-interfaces built on them, so those will have
to be pruned. create_bondethernet() will now create (or re-create)
the bond with the correct flags.
Unit-tests, YAML tests and the integration test all pass.
Updated config-guide.
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.
