A developer should be able to easily create a mobile-friendly / responsive dialog

Problem/Motivation

As documented in https://www.drupal.org/docs/develop/drupal-apis/ajax-api/ajax-dialog-boxes → AJAX dialog boxes cant take a "width" option but not a "max-width".

A maximum width is a much better thing to provide for dialogs to also work on various smaller screen sizes.

Steps to reproduce

Proposed resolution

Merge request link

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet