Add ETW for diagnosing parse time of scripts

Today, it is possible to diagnose the execution time of scripts but understanding which scripts are contributing to Parse/ByteCodeGen/JIT CPU costs can be difficult and requires correlation with other events.

It would be ideal if there were Events in Chakra that allows Parse/ByteCodeGen code to be timed and associated with a "user-friendly string" identifier for the script that is being acted upon.
(Perfect is the enemy of good and I'd rather have something functional and imperfect than something perfect for diagnosis here. :-))

@nolanlawson so he is aware.