The stories do not need CunninghamProvider anymore since it is
handled by the configuration for the themes support. Some stories
were also using wrong colors that didn't handle multiple themes.
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.
Rework a bit the recent work made on RHF example to make some component
more generic, such as RhfSelect and RhfDatepicker, which is based on a
design using RHF context hooks to provide a seamless integration.
Fixes#144
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.
