Add an onUpdated event

[WilliamStam]

right now we have onChange / change event but that gets fired on every selection of a multi select.

so say you want to run an event like "lookup some data on change" it becomes a bit more difficult since its basicaly going to run on every selection.

so then i got to try onDropdownClose but that fires before the change with a normal single select.

proposing adding in an event that checks the current value, if its different to to the "new" value, then run the callback when the dropdown closes.

[WilliamStam]

 onChange: (v)=>{
            console.log("onChange",v)
            // value.value = v;
        },
        onDropdownClose: ()=>{
            console.log("onDropdownClose")
            // emit('update:modelValue',value.value)
        }

for a multi select, selecting 3 items

onChange ['4']
onChange (2) ['4', '43']
onChange (3) ['4', '43', '10']
onDropdownClose

when its a single select

onDropdownClose
onChange 2

(not sure if this is a bug or not) it just gets kinda hard to "run a function when this have changed" in a sane way like this i think.

[oyejorge]

Looks like a bug to me. #288