backend/tests: Add blackbox tests from Kotlin JVM

Added tests from testData/codegen/box directory. There are blackbox tests
in other directories and they are to be added.

backend.native/tests/external/codegen/blackbox/arrays/iteratorLongArrayNextLong.kt

@@ -0,0 +1,13 @@
+// TODO: muted automatically, investigate should it be ran for JS or not
+// IGNORE_BACKEND: JS
+
+fun box(): String {
+    val a = LongArray(5)
+    val x = a.iterator()
+    var i = 0
+    while (x.hasNext()) {
+        if (a[i] != x.nextLong()) return "Fail $i"
+        i++
+    }
+    return "OK"
+}