Previously if the menu was opened and no there were no options to be
displayed it was just showing a tiny empty menu, this commit adds an
empty placeholder in order to make it clearer that the list is empty.
This new major version broke our components, including the way the menu
gets opened, how to determine the disabled options and some other semantic
types changes.
Adding this new variant makes necessary to reorganize the files to keep
a clear separations of concerns. As of now Select/index.tsx is just an
entrypoint to render either the mono or multi variant of the select.
