MultiSelect - option to select-all by default during creation

[conikeec]

Is your feature request related to a problem? Please describe.
There are cases where the multi-select list is fairly large (>20 items). Select each of item for larger lists can turn out to be a bad experience

Describe the solution you'd like
Ability to select-all from the multiselect list by default. Thereafter the use can dis-select items to remove which would rather easier to do for large lists

Describe alternatives you've considered
None

Additional context
None

[mikaelmello]

Done, should be merged soon! It might take a while to be officially released as there are some things in the works that will require special attention. Until then, you can either point your dependency to the merge commit or use something like .with_default(&((0..#option length here#).collect::<Vec<_>>())) which I know is quite the workaround :)