The Filter by Label search box isn't working for the Image Select element

Problem/Motivation

The search text filter isn't working when the "Include filter by label" option is enabled for the Image Select element; it does not filter images.

Steps to reproduce

1. Create an Image Select element.
2. Check the "Include filter by label" checkbox in the element settings.
3. Try to use the search text filter.

Proposed resolution

We have to edit the following file: /webform/modules/webform_image_select/webform_image_select.libraries.yml.
js/webform_image_select.element.js: {} should be replaced with js/webform_image_select.element.js: {weight: -1}.
This way, we will include webform.filter.js after webform_image_select.element.js to ensure that the $('.js-images-filter .thumbnails') element is available before webform.filter.js attempts to access it.