Tracer and profiler

[mturilli]

We need new/better tracing/profiling capabilities for RCT. We start with RP and then, based on the lessons learned and possibly the code produced, we will expand to other RCT components.

This presentation traces the work we are doing on RADICAL.Tracer, a new RCT component we are prototyping:
https://docs.google.com/presentation/d/1AJEmz7efiJRJxHVsYEmoZkvUvZq6vRt3sGkgtqh9utA/

As part of this activity, we should write unit and integration tests to check the completeness and integrity of the traces generated by RP (and then other RCT tools). Initial discussion about tests at #2302

[mturilli]

Other tickets to address with the new tracer in RP: #2195 #1959 #1521 #1451