Adding separator for multi select

[pkyad]

Is your feature request related to a problem? Please describe.
No

Describe the solution you'd like
In Node I have used separator to group items which are related like the following.

choices.push(new Separator());
choices.push(new Separator(Group name));

and it renders as

[JaydenElliott]

I also think this would be useful

[pkyad]

@mikaelmello can you please look at this opportunity to improve the multi select