Add Unit Tests to guarantee non Pip feature device quality

Since Android Go disabled PIP feature, the current PIP arch
register a bunch of callback at ctor, however, with dagger's
mechanism it's not easy to predict which pip components was inited
and register callback, that could introduce NPE unexpectly.
Adding more test to verify disabled pip is a good option

Adding new unit tests for PIP :
+ PipControllerTest
+ PipTaskOrganizerTest
+ OverviewProxyServiceTest

Test: atest PipControllerTest
Test: atest PipTaskOrganizerTest
Test: atest WMShellTest
Test: make SystemUI
Test: make ArcSystemUI
Test: make WMShellUnitTests
Test: lunch aosp_tv_arm-userdebug & make
Test: atest SystemUITests
Test: atest WindowManagerShellTests
Test: atest WMShellUnitTests
Test: adb shell input keyevent 171(KEYCODE_WINDOW)
Test: manual test Pip demo AP
Test: adb shell dumpsys activity service com.android.systemui

Bug: 168715160
Change-Id: Idee90d00265d2ced629d4ba4eb0bb85c2a7905ac