Add resizing tasks synchronously flicker tests

The test app will launch two tasks on two SurfaceViews and use
TaskOrganizer that implements BLASTSyncEngine to resize two
tasks synchronously.

We could verify it from the layersTrace to ensure the layers of the
two tasks could apply resizing at same transaction.

Bug: 168505972
Test: enable mUseBLASTSync, atest ResizeTasksSyncTest
Change-Id: I815325e37f3ce1e70fb5b51ec32f82a0088c4943