Expose the pieces the experimental monitor needs to share the same time
model as the stock profiler.
This adds Python bindings for the approximate clock, the
ApproximateClock-to-Unix-time converter, and the native CUPTI timestamp
callback entry point so monitor-collected activities can be normalized
and exported in the same wall-clock domain as CPU profiler events.
Pull Request resolved: #186035
Approved by: https://github.com/dolpm, https://github.com/scotts