interfaces: management address is set to pattern on exact match

interfaces: management address is set to pattern on exact match

When the management pattern is an exact IP address, use it as is instead
of trying to match an interface. When a user doesn't want this
behavior (keeping the check), they should use something like
`192.168.1.15,0` or `!*,!!192.168.1.15` instead of the exact IP address.

This feature allows a user to advertise an out-of-band management IP
address.

Closes #103