Migrate boxWithJava tests to multi-file framework

compiler/testData/codegen/boxWithJava/jvmOverloads/simple.kt

@@ -0,0 +1,18 @@
+// FILE: Test.java
+
+public class Test {
+    public static String invokeMethodWithOverloads() {
+        C c = new C();
+        return c.foo();
+    }
+}
+
+// FILE: simple.kt
+
+class C {
+    @kotlin.jvm.JvmOverloads public fun foo(o: String = "O", k: String = "K"): String = o + k
+}
+
+fun box(): String {
+    return Test.invokeMethodWithOverloads()
+}