Fix status bar assertions on seamless rotation

Status bar should not be visible because the app layer in seamless rotation is in full screen.

Also, add checks to ensure: app window is always full screen and app window is always set to seamless

Also: refactor rotation test assertions:
   - base class, all assertions in presubmit
   - child classes, override if need flaky or postsubmit

Bug: 186115871
Bug: 190350376
Test: atest FlickerTests:com.android.server.wm.flicker.rotation
Change-Id: I31f9c41ad6a8c0048a8f8a353c7e468afda1fc8e