test_runner: add Date to the supported mock APIs

signed-off-by: Lucas Santos <[email protected]>
PR-URL: nodejs#48638
Reviewed-By: Benjamin Gruenbaum <[email protected]>
Reviewed-By: Moshe Atlow <[email protected]>
Reviewed-By: Erick Wendel <[email protected]>
Reviewed-By: Rafael Gonzaga <[email protected]>
Reviewed-By: Antoine du Hamel <[email protected]>

Author: khaosdoctor