backend/tests: Add blackbox tests from Kotlin JVM

Added tests from testData/codegen/box directory. There are blackbox tests
in other directories and they are to be added.

backend.native/tests/external/codegen/blackbox/objects/objectInLocalAnonymousObject.kt

@@ -0,0 +1,10 @@
+fun box(): String {
+    var boo = "OK"
+    var foo = object {
+        val bar = object {
+            val baz = boo
+        }
+    }
+
+    return foo.bar.baz
+}