[4/n] Add fullscreen option in user aspect ratio settings

Apps > App Info > Advanced > Aspect ratio

Adds fullscreen option to aspect ratio settings gated by fullscreen
build time and runtime flags. If fullscreen option is disabled, return
app default option.

To enable feature:
adb shell device_config put window_manager
enable_app_compat_user_aspect_ratio_settings true
adb shell am force-stop com.android.settings

Bug: 291900454
Test: All Settings CUJs passed
      atest SettingsUnitTests:UserAspectRatioManagerTest
Change-Id: I8f8d0c08ac81f088d6c25e8dfb3550f807f336b6