[Profiler] Handle events from Kineto in the unified result class. (#80797)
At long last, `torch::profiler::impl::Result` can handle all data for the profiler. The principle change is that `collection.cpp` now extracts events that Kineto collected rather than `profiler_kineto.cpp`, and there is now an `ExtraFields<Kineto>` type added to the Result variant.
Differential Revision: [D37406956](https://our.internmc.facebook.com/intern/diff/D37406956/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/80797
Approved by: https://github.com/aaronenyeshi
