Option for human-readable DateTime in trace output

We added a DateTime field in addition to Time field in FDB3. This had several benefits:

1. It makes the traces more human readable without post-processing
2. When running simulator tests, it allows you to know the real time in which the test runs, and how long each step of the simulation takes to run, in addition to the simulated time.

for example:
{ "Severity": "10", "Time": "219.091258", "DateTime": "2020-09-03T02:35:33", "Machine": "1.0.1.5:4", "Type": "MachineLoadDetail", "ID": "0000000000000000", ..........

If we don't want to include DateTime in the output by default, we could add a commandline option or knob to include DateTime in the traces