Migrate boxWithJava tests to multi-file framework

compiler/testData/codegen/boxWithJava/interfaces/abstractClassInheritsFromInterface.kt

@@ -1,3 +1,13 @@
+// FILE: ExtendsKCWithT.java
+
+public class ExtendsKCWithT extends KC {
+    public static String bar() {
+        return new ExtendsKCWithT().foo();
+    }
+}
+
+// FILE: KC.kt
+
 // KT-3407 Implementing (in Java) an abstract Kotlin class that implements a trait does not respect trait method definition
 
 interface  T {

compiler/testData/codegen/boxWithJava/interfaces/abstractClassInheritsFromInterface/ExtendsKCWithT.java

@@ -1,5 +0,0 @@
-public class ExtendsKCWithT extends KC {
-    public static String bar() {
-        return new ExtendsKCWithT().foo();
-    }
-}

compiler/testData/codegen/boxWithJava/interfaces/inheritJavaInterface.kt

@@ -1,3 +1,12 @@
+// FILE: MyInt.java
+
+public interface MyInt {
+
+    String test();
+}
+
+// FILE: test.kt
+
 interface A : MyInt {
     override public fun test(): String? {
         return "OK"
@@ -8,4 +17,4 @@ class B: A
 
 fun box() : String {
     return B().test()!!
-}
+}

compiler/testData/codegen/boxWithJava/interfaces/inheritJavaInterface/MyInt.java

@@ -1,4 +0,0 @@
-public interface MyInt {
-
-    String test();
-}