lineage-sdk lights: add battery light isSupported() helper

*) Used by fw/b to prevent making LightsService
   calls when a battery light is not present.

Change-Id: I871a0fd3505e6f0b4db8eb6ba5971680c36a14c3

sdk/src/java/org/lineageos/internal/notification/LineageBatteryLights.java

@@ -35,6 +35,7 @@ public final class LineageBatteryLights {
     private final boolean DEBUG = false;
 
     // Battery light capabilities.
+    private final boolean mHasBatteryLed;
     private final boolean mMultiColorLed;
     private final boolean mUseSegmentedBatteryLed;
 
@@ -56,6 +57,10 @@ public final class LineageBatteryLights {
         mContext = context;
         mLedUpdater = ledUpdater;
 
+        // Does the device have a battery LED ?
+        mHasBatteryLed = LightsCapabilities.supports(
+                mContext, LightsCapabilities.LIGHTS_BATTERY_LED);
+
         // Does the device support changing battery LED colors?
         mMultiColorLed = LightsCapabilities.supports(
                 mContext, LightsCapabilities.LIGHTS_RGB_BATTERY_LED);
@@ -69,6 +74,10 @@ public final class LineageBatteryLights {
         observer.observe();
     }
 
+    public boolean isSupported() {
+        return mHasBatteryLed;
+    }
+
     public void calcLights(LedValues ledValues, int level, int status, boolean low) {
         if (DEBUG) {
             Slog.i(TAG, "calcLights input: ledValues={ " + ledValues + " } level="