Profiler API updates

I've added a few changes to the Profiler API, specifically:
- Modified: Separated Profiler formatting and making it configurable
- Modified: Encouraging Profiler immutability
- Modified: Making Profiler logging Marker configurable
- Added: API for finding/building Profilers that have been registered.
- Fixed: Updated Profiler logging output to support N-Depth Profiler nesting.