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/plusCollectionInference.kt

@@ -0,0 +1,15 @@
+import kotlin.test.*
+import kotlin.comparisons.*
+
+fun box() {
+    val listOfLists = listOf(listOf("s"))
+    val elementList = listOf("a")
+    val result: List<List<String>> = listOfLists.plusElement(elementList)
+    assertEquals(listOf(listOf("s"), listOf("a")), result, "should be list + element")
+
+    val listOfAny = listOf<Any>("a") + listOf<Any>("b")
+    assertEquals(listOf("a", "b"), listOfAny, "should be list + list")
+
+    val listOfAnyAndList = listOf<Any>("a") + listOf<Any>("b") as Any
+    assertEquals(listOf("a", listOf("b")), listOfAnyAndList, "should be list + Any")
+}