Investigate using `allow_block_list` to manage restricted nodes/sentry nodes

[MitchTurner]

https://docs.rs/libp2p/latest/libp2p/allow_block_list/struct.Behaviour.html#method.allow_peer

Currently we are using a custom authenticate with our transport. If we move the handling to our behaviors, our code can be more transport-independent.

[thomaseizinger]

This includes a tiny change in behaviour. A remote can observe that the authentication handshake failed and for them, the connection is thus never established.

With allow_block_list, the connection is seemingly established successfully from the perspective of the remote but closed instantly afterwards. Not sure if this matters for your usecase.

[MitchTurner]

Our authentication and checksum code is working currently, so I don't know that we need to prioritize this work.