Migrate boxWithJava tests to multi-file framework

compiler/testData/codegen/java8/box/inheritKotlin.kt

@@ -0,0 +1,31 @@
+// FILE: Simple.java
+
+interface Simple extends KInterface {
+    default String test() {
+        return "simple";
+    }
+}
+
+// FILE: main.kt
+
+interface KInterface {
+    fun test(): String {
+        return "base";
+    }
+}
+
+class Test : Simple {
+    fun bar(): String {
+        return super.test()
+    }
+}
+
+fun box(): String {
+    val test = Test().test()
+    if (test != "simple") return "fail $test"
+
+    val bar = Test().bar()
+    if (bar != "simple") return "fail 2 $bar"
+
+    return "OK"
+}