Adapt to new off-canvas dialog changes

Problem/Motivation

In Drupal 10.4 / 11, there are a number of changes that break the way we're using the off-canvas dialog that we need to adapt to. Here's an initial list:

• https://www.drupal.org/node/3422670 →
• https://www.drupal.org/node/3440844 →
• https://www.drupal.org/node/3426632 →
• https://www.drupal.org/node/3398575 →
• https://www.drupal.org/node/3358036 →

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes