WiiUpdateCallback: Add interface for update callback

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/utils/WiiUpdateCallback.java

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package org.dolphinemu.dolphinemu.utils;
+
+import androidx.annotation.Keep;
+
+public interface WiiUpdateCallback
+{
+  @Keep
+  boolean run(int processed, int total, long titleId);
+}