[Profiler] Memory profiler part 4: Select top level torch ops (#86880)
In a later PR we will walk the children of these nodes and formulate a node from the entire bundle to build a data flow graph. This PR simply defines what a "top level" op is.
Differential Revision: [D40220387](https://our.internmc.facebook.com/intern/diff/D40220387/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86880
Approved by: https://github.com/chaekit
