INT-3123 TCP Fix Error Propagation with Failover

The second chance NIO logic that detects a close being received
in a race condition with a reply needs to be enabled always because
a Failover or Caching connection factory might be using NIO
underneath.

Also, add an epoch to the FailoverTcpConnection's connectionId which
is incremented on each use to prevent a close after a previous
use being received by the current user.

Finally, add code in the FailoverTcpConnection to not propagate
messages from an old (defunct) delegate connection - if the
delegate has changed, the connection must be being used by
another client.