Coroutine tracing improvements

Replace stack-walking implementation in RepeatWhenAttached with
the one in the tracinglib library. Also, name a few of the flows
manually.

Test: Run demo app, capture trace, look for coroutine IDs
Flag: com.android.systemui.coroutine_tracing
Bug: 289353932
Change-Id: Iba51f42e2403fe3f4538929413b222c9f571b955