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/utils/LazyTest/alreadyInitialized.kt

@@ -0,0 +1,10 @@
+import kotlin.*
+import kotlin.test.*
+
+
+fun box() {
+    val lazyInt = lazyOf(1)
+
+    assertTrue(lazyInt.isInitialized())
+    assertEquals(1, lazyInt.value)
+}

backend.native/tests/external/stdlib/utils/LazyTest/initializationCalledOnce.kt

@@ -0,0 +1,17 @@
+import kotlin.*
+import kotlin.test.*
+
+
+fun box() {
+    var callCount = 0
+    val lazyInt = lazy { ++callCount }
+
+    assertEquals(0, callCount)
+    assertFalse(lazyInt.isInitialized())
+    assertEquals(1, lazyInt.value)
+    assertEquals(1, callCount)
+    assertTrue(lazyInt.isInitialized())
+
+    lazyInt.value
+    assertEquals(1, callCount)
+}

backend.native/tests/external/stdlib/utils/LazyTest/lazyToString.kt

@@ -0,0 +1,15 @@
+import kotlin.*
+import kotlin.test.*
+
+
+fun box() {
+    var callCount = 0
+    val lazyInt = lazy { ++callCount }
+
+    assertNotEquals("1", lazyInt.toString())
+    assertEquals(0, callCount)
+
+    assertEquals(1, lazyInt.value)
+    assertEquals("1", lazyInt.toString())
+    assertEquals(1, callCount)
+}