Blacklist malicious nodes

[herr-seppia]

Describe what you want implemented
A mechanism for a node to stop receiving messages from well-known malicious nodes.

Describe "Why" this is needed
If a node receive malicious messages (kadcast wellformed but invalid) there is no way at the moment of writing to prevent processing further messages from the sender.
This can potentially lead to a DOS attack consuming cpu/memory/bandwidth.

Describe alternatives you've considered
N/A

Additional context
A solution at kadcast level would be great in order to remove the peer from the routing table (avoiding to even broadcast messages to it mitigating a partial network eclipse)
Blacklisting should be local to avoid to introduce any network-wide security issue