Add support for PiP mode

platform/android/java/app/src/main/AndroidManifest.xml

@@ -35,6 +35,7 @@
             android:launchMode="singleInstancePerTask"
             android:excludeFromRecents="false"
             android:exported="false"
+            android:supportsPictureInPicture="true"
             android:screenOrientation="landscape"
             android:windowSoftInputMode="adjustResize"
             android:configChanges="layoutDirection|locale|orientation|keyboardHidden|screenSize|smallestScreenSize|density|keyboard|navigation|screenLayout|uiMode"

platform/android/java/app/src/main/java/com/godot/game/GodotApp.java

@@ -92,4 +92,9 @@ public class GodotApp extends GodotActivity {
 			super.onGodotForceQuit(instance);
 		}
 	}
+
+	@Override
+	protected boolean isPiPEnabled() {
+		return true;
+	}
 }