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/TuplesTest/pairToList.kt

@@ -0,0 +1,11 @@
+import kotlin.test.*
+import kotlin.test.assertTrue
+import kotlin.test.assertEquals
+import kotlin.test.assertNotEquals
+
+val t = Triple(1, "a", 0.07)
+fun box() {
+    assertEquals(listOf(1, 2), (1 to 2).toList())
+    assertEquals(listOf(1, null), (1 to null).toList())
+    assertEquals(listOf(1, "2"), (1 to "2").toList())
+}