Log the exception when the view couldn't get added

We are getting reports of a crash inside ViewRootImpl's
InputStage.onDetachedFromWindow method, due to 'mFirstInputStage' object
being null.

The only way that could happen is if 'mAdded' is true, but an exception
occurs sometime before 'mFirstInputStage' is assigned.

The most likely caller of this location is WindowManagerGlobal. Inside
WMG, there is a "try / catch" section. The actual exception is indeed
getting rethrown. However, because it's java, it's hard to trace whether
anyone else higher up is catching this exception.

Therefore, simply null checking the mFirstInputStage might be just
postponing this problem.

If we are going to throw anyways, then it's likely that try / catch
approach of WMG is not needed - we should just throw and not do the
"removeViewLocked" code.

In this CL, the proposal is to add a log of the exception as soon as it
occurs, so that we can learn more about the problem. We can then make a
more informed decision on how to handle it.

Bug: 385705687
Flag: EXEMPT refactor
Test: none
Change-Id: I3d239bcd5b84710325d33fff86d99a4be9a8dc3f