Migrate boxAgainstJava tests to multi-file framework

compiler/testData/codegen/boxAgainstJava/visibility/protectedStatic/funObject.kt

@@ -1,9 +1,19 @@
-object A: funObject() {
-  fun test(): String {
-    return funObject.protectedFun()!!
-  }
+// FILE: J.java
+
+public class J {
+    protected static String protectedFun() {
+        return "OK";
+    }
+}
+
+// FILE: 1.kt
+
+object A : J() {
+    fun test(): String {
+        return J.protectedFun()!!
+    }
 }
 
 fun box(): String {
-  return A.test()
+    return A.test()
 }