Views with node providers are important for accessibility in auto mode.

1. If a view's important for accessibility attribute is set to auto the
   framework is responsible to determine if it really is. Views with
   accessibility node providers should be important for accessibilty
   since they are roots of virtual view trees and such trees are
   always important.

bug:6843043

Change-Id: I4b352c59fdefdf9ad220714a43ecb9e01d1c1c1f