[ATF integration] include validator in layoutlib am: 9fc4e188f3 am: b643d07b96 am: 30954ee307

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/layoutlib/+/11493831

Change-Id: I3492e5b18f219b983cf7c49609b5590003b072bc