p2p: TODO or add peer ban behaviour

[redsh4de]

What

Add ban behaviours from monerod, or TODOs in places where bans would be needed but would require ban system upgrades.

Why

Consistency, documentation for future upgrades

Where

cuprated, p2p

How

New bans added for places where monerod drops connection with a ban score contribution (drop_connection(_,true,_)).

Action	Trigger	Precedent (v0.18.5.0)
SHORT_BAN	Duplicate tx index in fluffy missing-tx request	cryptonote_protocol_handler.inl:782-794
MEDIUM_BAN	Duplicate block IDs in chain response	cryptonote_protocol_handler.inl:2544-2549
MEDIUM_BAN	Empty block batch response	cryptonote_protocol_handler.inl:1071-1077

TODOs added in places where monerod contributes to the ban score accumulator (add_host_fail / hit_score), and triggers a ban only after repeated violations. Needs ban system upgrades, as currently it's either ban or do nothing.

Trigger	Precedent (v0.18.5.0)
current_blockchain_height regression (3 sites: new_fluffy_block, timed-sync request, timed-sync response)	cryptonote_protocol_handler.inl:466-470 cryptonote_protocol_handler.inl:1087-1091 cryptonote_protocol_handler.inl:2509-2513
Inbound handshake wrong network ID	net_node.inl:2587-2594
Outbound handshake invalid peerlist	net_node.inl:1170-1175
Timed-sync invalid peerlist	net_node.inl:1250-1255