* Use a named CancelHeartbeatTask unit struct for the channel type
* Prefer cancel handles in selects, if both are ready
* Fix message metrics to just show the command name
* Add metrics for internal requests and responses
* Add internal requests and responses to the messages dashboard
* Add a canceled metric, and peer addresses to request and response metrics
* Add a canceled messages graph
* Add connection state metrics for currently open connections
* Fix the connection state graph with new metrics
* Always send an error before dropping pending responses
* Move error detail logging into `fail_with`
* Delete an unused timer future
* Make error strings in metrics less verbose
* Downgrade some error logs to info
* Remove a redundant expect
* Avoid unnecessary allocations for connection state metrics
* Fix missed updates to mempool and block gossip metrics