Expose TCP connection time in metadata

[kgoodier]

The connectedMs field in the metadata is the time the request started relative to the time the connection started. Because we dispatch the first request into the socket and THEN do the connection, it is essentially 0 for the first request, and the total duration of that first request includes the TCP connection time.

Let's break out the TCP connection time into its own field. Maybe consider then subtracting that time from the duration of the first request.