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/createWithSelector.kt

@@ -0,0 +1,10 @@
+import kotlin.test.*
+
+
+fun box() {
+    val map = listOf("a", "bb", "ccc").associateBy { it.length }
+    assertEquals(3, map.size)
+    assertEquals("a", map.get(1))
+    assertEquals("bb", map.get(2))
+    assertEquals("ccc", map.get(3))
+}