startObservingLifecycleIfNeeded

Starts the size/time-based flush and app-backgrounding observers. Safe to call more than once, and safe to call from any thread: Lifecycle.addObserver requires the main thread, so registration is dispatched there rather than trusting every caller (this is invoked from com.framepayments.framesdk.FrameNetworking.initializeWithAPIKey, a plain function a host could call from a background thread).