add wireless charger support

bug: 6879638

- add new enum value BATTERY_PLUGGED_WIRELESS
- check for sys online file with contents "Wireless"

Change-Id: I22dc3c40f50573c98643e7b5cbcb237d0216530d
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 6dbba46..28273f0 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -1147,6 +1147,7 @@
          * <li>{@code 0} to never stay on while plugged in</li>
          * <li>{@link BatteryManager#BATTERY_PLUGGED_AC} to stay on for AC charger</li>
          * <li>{@link BatteryManager#BATTERY_PLUGGED_USB} to stay on for USB charger</li>
+         * <li>{@link BatteryManager#BATTERY_PLUGGED_WIRELESS} to stay on for wireless charger</li>
          * </ul>
          * These values can be OR-ed together.
          */