FIX Apply multiupload auto-detection for upload fields

[GuySartorelli]

UploadField checks hasone components based on the field name to see if it can be a multiUpload field or not. We need to trigger that before changing the name of the field.

Issue

• Upload field multi selection auto detection breaking with inline editor #1104

[emteknetnz]

Well that was easy :-)

Tested locally, works good

[emteknetnz]

In case anyone's interested here's the code I used to validate the before and after

<?php

use DNADesign\Elemental\Models\BaseElement;
use SilverStripe\Assets\File;
use SilverStripe\AssetAdmin\Forms\UploadField;

class MyElement extends BaseElement
{
    private static array $has_one = [
        'MyFile' => File::class
    ];

    public function getType()
    {
        return 'My block';
    }

    public function getCMSFields()
    {
        $fields = parent::getCMSFields();
        $fields->addFieldToTab('Root.Main', new UploadField('MyFile', 'MyFile'));
        return $fields;
    }
}