network/ipv4acd: manage ACD engines with Address object

network/ipv4acd: manage ACD engines with Address object

IPv4 addresses are managed with local and peer addresses and prefix
length. So, potentially, the same address with different prefix length
can be assigned on a link, e.g. 192.168.0.1/24 and 192.168.0.1/26.
If one of the address is configured with ACD but the other is not,
then previously ACD might be unexpectedly disabled or enabled on them,
as we managed ACD engines with only local addresses.

This makes ACD engines managed with the corresponding Address objects.