The oveflowing labels were spreading on two lines. I had to wrap a
span inside a label in order to be able to deal with the text-oveflow
plus the absolute positionning.
Previsouly when selecting item A and then removing it, it was impossible
to select it again. This was caused by the internal memory of useSelect
that only provides undefined selectedItem inside the onStateChange callback
when the item has not changed. So by forcing it everytime to null it is
now providing it everytime.
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.
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.
