Add current form data as second argument to RecordFinder scope method

[mjauvin]

It can be useful if the record finder needs some other fields in the form to filter its values.

Related: wintercms/docs#256

E.g. fields definition:

country:
    type: dropdown

state:
    type: recordfinder
    list: $/author/plugin/models/state/columns.yaml
    scope: statesByCountry

class State extends model
{
    public function scopeStatesByCountry($query, $model, $formData)
    {
        if ($country_id = array_get($formData, 'country')) {
            $query->where('country_id', $country_id);
        }
    }
}

[AIC-BV]

Works perfectly! Thanks!!!

public function scopeWhereProduct($query, $model, $formData)
{
    if ($productId = array_get($formData, 'product')) {
        return $query->where('product_id', $productId);
    }
    return $query->where('product_id', null); // returns an empty list in my case, so they will be forced to select a product first ;)
}

[AIC-BV]

@mjauvin can this be merged?
I had trouble because I ran composer update

[mjauvin]

@AIC-BV did you test this PR as well?

[AIC-BV]

@AIC-BV did you test this PR as well?

I copied the change to my local file and deployed it in production since Jan 18
Works perfectly

[mjauvin]

@LukeTowers any objection in merging this? There's a PR to the docs also in the description.