[5.0] Prometheus: Add stable identifier for P2P connections

[heifner]

Use the node_id as a stable identifier for P2P connections in prometheus_plugin. The previous connid_# would change on each disconnect/connect.

Example output:

nodeos_p2p_addr{address="localhost:9877 - 539b1ae",connid="539b1ae",ipv6="::ffff:127.0.0.1"} 0
nodeos_p2p_addr{address="localhost:9776 - 9069fa8",connid="9069fa8",ipv6="::ffff:127.0.0.1"} 0
# HELP nodeos_p2p_port port
# TYPE nodeos_p2p_port gauge
nodeos_p2p_port{connid="539b1ae"} 60836
nodeos_p2p_port{connid="9069fa8"} 9776
# HELP nodeos_p2p_connection_number monatomic increasing connection number
# TYPE nodeos_p2p_connection_number gauge
nodeos_p2p_connection_number{connid="539b1ae"} 3
nodeos_p2p_connection_number{connid="9069fa8"} 1
# HELP nodeos_p2p_accepting_blocks accepting blocks on connection
# TYPE nodeos_p2p_accepting_blocks gauge
nodeos_p2p_accepting_blocks{connid="539b1ae"} 1
nodeos_p2p_accepting_blocks{connid="9069fa8"} 1
# HELP nodeos_p2p_last_received_block last received block on connection
# TYPE nodeos_p2p_last_received_block gauge
nodeos_p2p_last_received_block{connid="539b1ae"} 583
nodeos_p2p_last_received_block{connid="9069fa8"} 316
# HELP nodeos_p2p_first_available_block first block available from connection
# TYPE nodeos_p2p_first_available_block gauge
nodeos_p2p_first_available_block{connid="539b1ae"} 0
nodeos_p2p_first_available_block{connid="9069fa8"} 0
# HELP nodeos_p2p_last_available_block last block available from connection
# TYPE nodeos_p2p_last_available_block gauge
nodeos_p2p_last_available_block{connid="539b1ae"} 9
nodeos_p2p_last_available_block{connid="9069fa8"} 6
# HELP nodeos_p2p_unique_first_block_count number of blocks first received from any connection on this connection
# TYPE nodeos_p2p_unique_first_block_count gauge
nodeos_p2p_unique_first_block_count{connid="539b1ae"} 0
nodeos_p2p_unique_first_block_count{connid="9069fa8"} 49
# HELP nodeos_p2p_latency last calculated latency with connection
# TYPE nodeos_p2p_latency gauge
nodeos_p2p_latency{connid="539b1ae"} 1225407
nodeos_p2p_latency{connid="9069fa8"} 1603551
# HELP nodeos_p2p_bytes_received total bytes received on connection
# TYPE nodeos_p2p_bytes_received gauge
nodeos_p2p_bytes_received{connid="539b1ae"} 116491
nodeos_p2p_bytes_received{connid="9069fa8"} 124636
# HELP nodeos_p2p_last_bytes_received last time anything received from peer
# TYPE nodeos_p2p_last_bytes_received gauge
nodeos_p2p_last_bytes_received{connid="539b1ae"} 1.69703998090273e+18
nodeos_p2p_last_bytes_received{connid="9069fa8"} 1.697039987312463e+18
# HELP nodeos_p2p_bytes_sent total bytes sent to peer
# TYPE nodeos_p2p_bytes_sent gauge
nodeos_p2p_bytes_sent{connid="539b1ae"} 342367
nodeos_p2p_bytes_sent{connid="9069fa8"} 289252
# HELP nodeos_p2p_last_bytes_sent last time anything sent to peer
# TYPE nodeos_p2p_last_bytes_sent gauge
nodeos_p2p_last_bytes_sent{connid="539b1ae"} 1.697039988851183e+18
nodeos_p2p_last_bytes_sent{connid="9069fa8"} 1.69703998885119e+18
# HELP nodeos_p2p_connection_start_time time of last connection to peer
# TYPE nodeos_p2p_connection_start_time gauge
nodeos_p2p_connection_start_time{connid="539b1ae"} 1.697039480900622e+18
nodeos_p2p_connection_start_time{connid="9069fa8"} 1.697039478899002e+18

Resolves #1683