Add Portrait/Landscape support for NexusLauncher screenshot tests

Updating @PortraitLandscape annotation to be public to allow its usage by modules implementing Launcher3 and AbstractLauncherUiTest and interop with Kotlin.

Bug: 283751050
Flag: N/A
Test: atest HomeScreenEditStateImageTest
Change-Id: I84e1210c0476a3b3f9b40bbb6ee6b46a44b752ff