[3.x] Set position on multi selects

[haringsrob]

Port of #2167

[haringsrob]

@ifox @antonioribeiro

I had to add this chunk of js to ensure that the options are set to the order of how the id's come in. I believe this also needs to be in 2.x as otherwise it will take the order of all the available options (which is not sorted)

[ifox]

@antonioribeiro can you share more about your use case for storing the position on multiselect? How are you using the field: which options do you use and how are the values loaded?

[ifox]

ping @antonioribeiro

[antonioribeiro]

Hey @ifox, use case is basically when we need to read the selected items in the order we are selecting them.

On the screenshot below I selected "Education" first, because I want Education to be shown as the main sector in my blog post page.

When I save and reload the model, Education is no more the first item and the frontend will show "Housing" as the main sector:

It doesn't really matter how I'm getting these records later because their positions are all null on the relationship table:

There will be no way for me to read them in the right order.

[antonioribeiro]

This is how I'm creating the form field to test on Twill 3, where I get the same behaviour:

$form->add(
    MultiSelect::make()
        ->name("sectors")
        ->inline()
        ->options(
            Options::make(
                Sector::all()
                    ->map(
                        fn($sector) => Option::make(
                            $sector->id,
                            $sector->title
                        )
                    )
                    ->toArray()
            )
        )
);