Migrate boxAgainstJava tests to multi-file framework

compiler/testData/codegen/boxAgainstJava/visibility/protectedStatic/simpleClass2.kt

@@ -1,9 +1,26 @@
-class Derived(): simpleClass2.A() {
+// FILE: Base.java
+
+public class Base {
+    public static class A {
+        protected static class B {
+            public B() {
+            }
+
+            public String foo() {
+                return "OK";
+            }
+        }
+    }
+}
+
+// FILE: 1.kt
+
+class Derived : Base.A() {
     fun test(): String {
-        return simpleClass2.A.B().foo()!!
+        return Base.A.B().foo()!!
     }
 }
 
 fun box(): String {
-   return Derived().test()
+    return Derived().test()
 }