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/CollectionTest/plusCollectionBug.kt

@@ -0,0 +1,7 @@
+import kotlin.test.*
+import kotlin.comparisons.*
+
+fun box() {
+    val list = listOf("foo", "bar") + listOf("cheese", "wine")
+    assertEquals(listOf("foo", "bar", "cheese", "wine"), list)
+}