Modify desktop windowing exemption logic and criteria

Modify modal exemption logic for desktop windowing to only check for
translucent activities and not floating activities as apps in desktop
windowing are freeform and thus meet the floating criteria.

Unify modal and systemUi activity exemption under one condition for
all ineligible activities to reduce individual checks required to
exempt current activities and any that may be needed in the future.

Flag: com.android.window.flags.enable_desktop_windowing_modals_policy
Fixes: 286929122
Fixes: 347739178
Bug: 347289970
Test: atest WMShellUnitTests:DesktopModeWindowDecorViewModelTests
Test: atest WMShellUnitTests:DesktopTasksControllerTest
Test: atest WMShellUnitTests:AppCompatUtilsTest

Change-Id: I29a415f2922b5eafd7008d87a984e495d1ca7ef0