feat(background-mode): add disableBatteryOptimizations function (#3235)

implemented disableBatteryOptimizations() method #3085

src/@ionic-native/plugins/background-mode/index.ts

@@ -267,4 +267,13 @@ export class BackgroundMode extends IonicNativePlugin {
     sync: true
   })
   unlock(): void {}
+
+  /**
+   * Disables battery optimazation mode for the app (android only)
+   */
+  @Cordova({
+    platforms: ['Android'],
+    sync: true
+  })
+  disableBatteryOptimizations(): void {}
 }