fix: assign addresses with a non-unique role to every interface

[semx]

Fixes the anycast half of #344.

The anycast branch logs that the address can be assigned to multiple interfaces at the same time and then skips the assignment, so the second VM sharing the address never gets it. Now this interface gets an object of its own carrying the same role, and the object already on the other interface is left alone.

Two things came out of it. The check only knew anycast, but NetBox exempts vip, vrrp, hsrp, glbp and carp from its uniqueness rule for the same reason, so all six are handled. And it read the role as data.role.value, which only matches what the API returns - an object we created ourselves holds the plain string, so our own anycast addresses were not recognised on a later run. Both shapes are read now. The removal path had the same narrow check and uses the same set.

The role is only set on an object we create, never written onto an existing one, since that is the user's to decide.

Plain duplicates without such a role still produce the old warning. That is the VLAN case from the first post in #344, and @Azmodeszer said he can live with it. It needs a config switch to change, tell me if you want one and I'll add it.

tests/test_ip_non_unique_roles.py: 7 of 8 fail on development, all pass here, including a control that a second run reuses the object instead of creating another one. Suite 112.