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/kt513.kt

@@ -0,0 +1,24 @@
+import java.util.*
+
+class A() {
+    fun <T> ArrayList<T>.add3(el: T) = add(el)
+
+    fun test(list: ArrayList<Int>) {
+        for (i in 1..10) {
+          list add3 i
+        }
+    }
+}
+
+fun <T> ArrayList<T>.add2(el: T) = add(el)
+
+fun box() : String{
+    var list = ArrayList<Int>()
+    for (i in 1..10) {
+      list add  i
+      list add2 i
+    }
+    A().test(list)
+    System.out?.println(list)
+    return "OK"
+}