feat(wire): rename ConnectionKind::Regular to OutboundFullRelay, add BlockRelayOnly and AddrFetch

[Sandipmandal25]

Description and Notes

Renames ConnectionKind::Regular to OutboundFullRelay and adds BlockRelayOnly and AddrFetch variants to align with Bitcoin Cores connection_type strings in getpeerinfo.

Changes

• Rename Regular(ServiceFlags) to OutboundFullRelay(ServiceFlags)

• Add BlockRelayOnly(ServiceFlags) for block-relay-only anchor peers

• Add AddrFetch for short-lived address discovery connections

• Extra now serializes as "block-relay-only"

• Add peer limits to NodeContext:

  • MAX_FULL_RELAY_PEERS

  • MAX_BLOCKS_ONLY_PEERS

  • MAX_MANUAL_PEERS

  • Update connection selection logic:

  • maybe_open_connection selects OutboundFullRelay or BlockRelayOnly based on available full relay slots

  • maybe_open_connection_with_added_peers applies MAX_MANUAL_PEERS based on connected peers

• upgrade:

  • When an Extra peer delivers new headers, it is promoted to OutboundFullRelay or BlockRelayOnly depending on available slots
  • If needed, the lowest-scoring peer of that type is replaced
  • If no peer of that type exists, promotion happens in place

• Replace .unwrap() with ? in check_for_stale_tip

• Add WireError::OutboundPeersExceeded

Result

The connection_type field in getpeerinfo rpc responses right now matches Bitcoin Core values:

• outbound full relay
• block relay only
• manual
• feeler
• addrfetch

Closes #623

[Sandipmandal25]

Friendly ping @Davidson-Souza @jaoleal