[Feature Request] Combobox: Emit an event on item creation

[totakoko]

Problem to solve

When using a Combobox with multiple values, it is currently not possible to know when a new item is created (that is an item not in the list).
The only way to know this information would be to compute the difference between the selected items and the whole list.

Proposed solution

The component could emit a "new-item" event when a new item gets created.

[KaelWD]

Duplicate of #4054

[totakoko]

I'm not sure this is a duplicate as I'm not interested in getting notified when a item is selected or deselected, I only want to get notified when a new item is created. I think this is only valid with combobox.

The use case would be to save and persist this new item so it can be reused in the list of the combobox.

I've committed a simple fix which seems to work.
May I make a PR for this ?

[KaelWD]

I think if we're adding the other two might as well have this too, although the workaround is much simpler than diffing the items like you need for autocomplete.

[bernardocs]

This featured (with @totakoko fix) proved very useful...
Thx :))

[johnleider]

Duplicate of #5682?