Migrate boxAgainstJava tests to multi-file framework

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

@@ -1,11 +1,21 @@
-class A {
-  companion object: funClassObject() {
-    fun test(): String {
-      return funClassObject.protectedFun()!!
+// FILE: J.java
+
+public class J {
+    protected static String protectedFun() {
+        return "OK";
+    }
+}
+
+// FILE: 1.kt
+
+class A {
+    companion object : J() {
+        fun test(): String {
+            return J.protectedFun()!!
+        }
     }
-  }
 }
 
 fun box(): String {
-  return A.test()
+    return A.test()
 }