network/address: make Address object more consistent with assigned address

network/address: make Address object more consistent with assigned address

This makes `manager_rtnl_process_address()`
- first read minimal information to get managed Address object,
- then update the managed Address object directly.

Previously, we updated the Address object managed by Link partially,
e.g. peer address did not updated.
This makes the managed Address object more consistent with the assigned
address.