Migrate boxWithJava tests to multi-file framework

compiler/testData/codegen/boxWithJava/casts/javaTypeIsFunK.kt

@@ -0,0 +1,16 @@
+// FILE: JFun.java
+
+class JFun implements kotlin.jvm.functions.Function0<String> {
+    public String invoke() {
+        return "OK";
+    }
+}
+
+// FILE: test.kt
+
+fun box(): String {
+    val jfun = JFun()
+    val jf = jfun as Any
+    if (jf is Function0<*>) return jfun()
+    else return "Failed: jf is Function0<*>"
+}

compiler/testData/codegen/boxWithJava/casts/javaTypeIsFunK/JFun.java

@@ -1,5 +0,0 @@
-class JFun implements kotlin.jvm.functions.Function0<String> {
-    public String invoke() {
-        return "OK";
-    }
-}

compiler/testData/codegen/boxWithJava/casts/javaTypeIsFunK/javaTypeIsFunK.kt

@@ -1,6 +0,0 @@
-fun box(): String {
-    val jfun = JFun()
-    val jf = jfun as Any
-    if (jf is Function0<*>) return jfun()
-    else return "Failed: jf is Function0<*>"
-}

compiler/testData/codegen/boxWithJava/casts/literalExpressionAsGenericArgument.kt

@@ -1,3 +1,5 @@
+// FILE: Box.java
+
 public class Box<T> {
     private final T value;
 
@@ -12,4 +14,11 @@ public class Box<T> {
     public T getValue() {
         return value;
     }
-}
+}
+
+// FILE: test.kt
+
+fun box(): String {
+    val sub = Box<Long>(-1)
+    return if (sub.value == -1L) "OK" else "fail"
+}

compiler/testData/codegen/boxWithJava/casts/literalExpressionAsGenericArgument/literalExpressionAsGenericArgument.kt

@@ -1,4 +0,0 @@
-fun box(): String {
-    val sub = Box<Long>(-1)
-    return if (sub.value == -1L) "OK" else "fail"
-}