Move blackBoxFile() testData to box/ directory

Delete all test methods (and empty test classes), since they'll be
auto-generated

compiler/testData/codegen/box/controlStructures/kt237.kt

@@ -0,0 +1,41 @@
+fun main(args: Array<String>?) {
+    val y: Unit = Unit.VALUE //do not compile
+    A<Unit>()        //do not compile
+    C<Unit>(Unit.VALUE)      //do not compile
+        //do not compile
+    System.out?.println(fff<Unit>(Unit.VALUE))  //do not compile
+    System.out?.println(id<Unit>(y))  //do not compile
+    System.out?.println(fff<Unit>(id<Unit>(y)) == id<Unit>(foreach(Array<Int>(0,{0}),{(e : Int) : Unit -> })))  //do not compile
+}
+class A<T>()
+
+class C<T>(val value: T) {
+    fun foo(): T = value
+}
+
+fun <T> fff(x: T) : T { return x }
+
+fun <T> id(value: T): T = value
+
+fun foreach(array: Array<Int>, action: (Int)-> Unit) {
+    for (el in array) {
+       action(el) //exception through compilation (see below)
+    }
+}
+
+fun almostFilter(array: Array<Int>, action: (Int)-> Int) {
+    for (el in array) {
+       action(el)
+    }
+}
+
+fun box() : String {
+    val a = Array<Int> (3,{-1})
+    a[0] = 0
+    a[1] = 1
+    a[2] = 2
+    foreach(a, { (el : Int) : Unit -> System.out?.println(el) })
+    almostFilter(a, { (el : Int) : Int -> el })
+    main(null)
+    return "OK"
+}