Make parents important for Content Capture

A view is important for content capture, its parents are also important
for content capture. So sets the cache of its parents become important
for content capture and send out its parent's appeared event.

Bug: 180059047
Test: manual
  1.new conversation and receive new message
  2.switch between different conversations
   check sent events for fullly view hierarchy
Test: atest CtsContentCaptureServiceTestCases
Change-Id: I700989650dd36555841d65d74e532f001e419416