Detect findViewTreeLifecycleOwner in RecyclerView.ViewHolder

[jzbrooks]

Since children of the recycler view aren't always attached to a context (like those coming into or leaving the screen), findViewTreeLifecycleOwner might return null. Ideally, these views wouldn't need to launch a coroutine, but those that do should depend on a more reliable coroutine scope than the view tree lifecycle owner's coroutine scope.