Conngater should support banning IP address

[matjazv]

Description

Currently conngater only supports banning peer IDs or permanently blocking IPs. We should be able to ban peer IP for a predefined time interval.

Acceptance Criteria

• It is possible to ban IP for a predefined time interval.
• All new code is unit tested.

Additional Information

• Revisit function names in conngater.go file and rename them if necessary
• Example: listBlockedPeers -> listBannedPeers?