Bugfix: Adds graceful peer disconnection (#5669)

The XRPL establishes connections in three stages: first a TCP connection, then a TLS/SSL handshake to secure the connection, and finally an upgrade to the bespoke XRP Ledger peer-to-peer protocol. During connection termination, xrpld directly closes the TCP connection, bypassing the TLS/SSL shutdown handshake. This makes peer disconnection diagnostics more difficult - abrupt TCP termination appears as if the peer crashed rather than disconnected gracefully.

This change refactors the connection lifecycle with the following changes:
- Enhanced outgoing connection logic with granular timeouts for each connection stage (TCP, TLS, XRPL handshake) to improve diagnostic capabilities
- Updated both PeerImp and ConnectAttempt to use proper asynchronous TLS shutdown procedures for graceful connection termination

Author: Tapanito