Support migration_inbound_addr in addition to live_migration_inbound_addr

[Nobuto Murata]

The charm has support of assigning a dedicated network space for live_migration_inbound_addr already:
- https://docs.openstack.org/nova/latest/configuration/config.html#libvirt.live_migration_inbound_addr
- https://bugs.launchpad.net/charm-nova-compute/+bug/1680531

However, the option wasn't enough to cover some supplementary traffic during the pre/post live-migration tasks and/or cold migration traffic. And a workaround has been implemented to allow SSH both in the main and migration networks in:
https://bugs.launchpad.net/charm-nova-cloud-controller/+bug/1969971

Now the upstream introduced a new config option "migration_inbound_addr" (for 2024.1) so we should support that to move out those high-volume traffic from the main management network.
- https://blueprints.launchpad.net/nova/+spec/libvirt-migrate-with-hostname-instead-of-ip
- https://docs.openstack.org/nova/latest/configuration/config.html#libvirt.migration_inbound_addr