Invisible views should not be visible to accessibility services (interrogation)

1. Infisible children of a ViewGroup are reported by View group
   while constructing an AccessibilityNodeInfo.

2. AncestorView does not check whether a found view is shown before
   returining it or perform action on it.

bug:4672230
Change-Id: Ic620ea71b7755c598407bdd813a2beeee400c89c