Fix tooltip handling for invisible and overlapping views

Ignore invisible views. Allow overlapping views to handle
dispatchTooltipHoverEvent in top-to-bottom order.

This brings the tooltip event handling method in line with
the existing touch and hover dispatch.

Bug: 34124732
Test: android.view.cts.TooltipTest#testMouseHoverOverlap
Change-Id: I37213318115dd2bb66979dac0f63f96e7221e8d7