Fabric: Implemetation of <Switch> component

Summary:
This is pretty straightforward implementation uses native `UISwitch`.
Suddenly we need Switch to test a bunch of other things.

Reviewed By: fkgozali

Differential Revision: D8344055

fbshipit-source-id: cfc51b8bc11198eb9d4d5e4745b96fb3a7f14de1

ReactCommon/fabric/components/switch/tests/SwitchTest.cpp

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <memory>
+
+#include <gtest/gtest.h>
+
+TEST(SwitchTest, testSomething) {
+  // TODO
+}