tests: Copy stdlib tests from Kotlin/JVM

This patch copies Kotlin/JVM stdlib tests (libraries/stdlib/test)
excepting ones with explicit java dependencies. It also transforms
the tests to use them as box-tests.

backend.native/tests/external/stdlib/collections/MapTest/iterate.kt

@@ -0,0 +1,14 @@
+import kotlin.test.*
+
+
+fun box() {
+    val map = mapOf("beverage" to "beer", "location" to "Mells", "name" to "James")
+    val list = arrayListOf<String>()
+    for (e in map) {
+        list.add(e.key)
+        list.add(e.value)
+    }
+
+    assertEquals(6, list.size)
+    assertEquals("beverage,beer,location,Mells,name,James", list.joinToString(","))
+}