add fair_dev packages (#1097)

Co-authored-by: Min Xu <min.xu.public@gmail.com>

fairscale/experimental/tooling/__init__.py

+# Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
+#
+# This source code is licensed under the BSD license found in the
+# LICENSE file in the root directory of this source tree.
+
+from typing import List
+
+__all__: List[str] = []

fairscale/fair_dev/__init__.py

+# Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
+#
+# This source code is licensed under the BSD license found in the
+# LICENSE file in the root directory of this source tree.
+
+from typing import List
+
+__all__: List[str] = []

fairscale/fair_dev/testing/__init__.py

+# Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
+#
+# This source code is licensed under the BSD license found in the
+# LICENSE file in the root directory of this source tree.
+
+from typing import List
+
+__all__: List[str] = []