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/partition.kt

@@ -0,0 +1,10 @@
+import kotlin.test.*
+import kotlin.comparisons.*
+
+fun box() {
+    val data = listOf("foo", "bar", "something", "xyz")
+    val pair = data.partition { it.length == 3 }
+
+    assertEquals(listOf("foo", "bar", "xyz"), pair.first, "pair.first")
+    assertEquals(listOf("something"), pair.second, "pair.second")
+}