Block ea_fileupload_widget improvements

Describe the bug
The block ea_fileupload_widget should get some improvements to comply with some field configuration:

Comply with field enable/disable status:

            <button type="button" class="btn btn-secondary btn-sm ea-fileupload-add-btn {{ not showAddButton ? 'd-none' }}" data-ea-fileupload-add{{ disabled ? ' disabled' }}>

{{ fileUrl }} should be configurable, especially for the thumbnail.
Currently the thumbnail load images of original size which is not optimized, I'd like to passe a custom thumbnail URL that could point out to LiipImagineBundle or anything else.

In my opinion the following piece of code should be a dedicated twig block allowing configurable thumbnail:

                    <div class="ea-fileupload-card-preview">
                        {% if isImage and fileUrl %}
                            <img src="{{ fileUrl }}" alt="{{ fileName }}" class="ea-fileupload-card-thumbnail" />
                        {% else %}
                            <twig:ea:Icon name="filetypes:{{ filetypeIcon }}" class="ea-fileupload-card-icon" />
                        {% endif %}
                    </div>

The same would apply for <div class="ea-fileupload-card-actions"> that is currently opening a new tab, a custom block would allow targeted override instead of extending the whole ea_fileupload_widget block.

I can make a PR if you're okay with the suggestion Javier ?

To Reproduce
Steps to reproduce this error and also, the EasyAdmin version used.

(OPTIONAL) Additional context
If they are useful, include logs, code samples, screenshots, etc.

Start at the ea_fileupload_widget Twig block shown in the issue and trace how field enable/disable state and fileUrl reach the widget. Done means the add control respects disabled fields, thumbnails can use a configurable URL, and the preview and actions areas can be overridden without extending the whole widget; add or update coverage if the project has tests for this block.