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/text/StringTest/replaceFirst.kt

@@ -0,0 +1,16 @@
+import kotlin.test.*
+
+
+
+fun box() {
+    val input = "AbbabA"
+    assertEquals("Abb${'$'}bA", input.replaceFirst('a','$'))
+    assertEquals("${'$'}bbabA", input.replaceFirst('a','$', ignoreCase = true))
+    // doesn't pass in Rhino JS
+    // assertEquals("schrodinger", "schrÖdinger".replaceFirst('ö', 'o', ignoreCase = true))
+
+    assertEquals("Abba${'$'}", input.replaceFirst("bA", "$"))
+    assertEquals("Ab${'$'}bA", input.replaceFirst("bA", "$", ignoreCase = true))
+
+    assertEquals("-test", "test".replaceFirst("", "-"))
+}