Add temp flag for lockscreen/aod ui prototyping

Add new Settings.Global.SHOW_NEW_LOCKSCREEN property. When enabled, new
lockscreen & aod UI + transitions will show. This is a temporary flag for the
purposes of protoyping which will be removed before release. Therefore, it should
not be backed up.

To toggle the flag (value = 0 is disabled, value = 1 is enabled):
adb shell settings put global show_new_lockscreen <value>

Test: manual
Bug: 170228350
Change-Id: I3b40b1de9bb80d43218fa1e8661fba47b50e9888

core/java/android/provider/Settings.java

@@ -14529,6 +14529,15 @@ public final class Settings {
          */
         public static final String SHOW_PEOPLE_SPACE = "show_people_space";
 
+        /**
+         * Whether to show new lockscreen & AOD UI.
+         * Values are:
+         * 0: Disabled (default)
+         * 1: Enabled
+         * @hide
+         */
+        public static final String SHOW_NEW_LOCKSCREEN = "show_new_lockscreen";
+
         /**
          * Block untrusted touches mode.
          *

packages/SettingsProvider/test/src/android/provider/SettingsBackupTest.java

@@ -440,6 +440,7 @@ public class SettingsBackupTest {
                     Settings.Global.SHOW_NEW_APP_INSTALLED_NOTIFICATION_ENABLED,
                     Settings.Global.SHOW_NOTIFICATION_CHANNEL_WARNINGS,
                     Settings.Global.SHOW_PEOPLE_SPACE,
+                    Settings.Global.SHOW_NEW_LOCKSCREEN,
                     Settings.Global.SHOW_RESTART_IN_CRASH_DIALOG,
                     Settings.Global.SHOW_TEMPERATURE_WARNING,
                     Settings.Global.SHOW_USB_TEMPERATURE_ALARM,