[Improvement] Add a `stackLimit` prop

There would be nice to have a way of controlling the max number of toasts displayed in the `stacked` layout to avoid issues like: #1171.

For example I would like to have at most 3 stacked toasts that when hovered maybe reveal the 100 total toasts to improve the ergonomics of the page. The users see there are "waiting" toasts, but maybe they don't want half of the screen always covered by toasts, only on hover.