Page title ellipsis accessibility issue

Problem/Motivation

• Copied from Gin Page Title Ellipsis Accessibility Issue.
• Originally reported by @joville (Jo Spelbrink)
• @mgifford and @rkoller added to the discussion in the original issue. I thought I saw a related issue for Default Admin, but I couldn't find it.

If you have a page title overflow the line, then you get get an Accessibility-Issue (SC 1.4.12: Text Spacing - Level AA). Because the title is getting cut off and cannot be accessed in full length in any way.

See: https://www.w3.org/WAI/WCAG22/Understanding/text-spacing.html#use-of-ell...

This is especially apparent on smaller viewports where even reasonable-length titles can get truncated.

Steps to reproduce

1. Standard installation.
2. Apply the Article test recipe (drush recipe core/tests/fixtures/recipes/article_content_type).
3. Log in as admin.
4. Go to /node/add/article.
5. Enter a long page title.
6. Save the node.
7. Reduce viewport width until the page title is truncated and an ellipsis appears.

Originally-reported case: Commerce environment if cancelling a subscription - the title is getting cut off.

Proposed resolution

The proposed solution is to discuss:

- Add a possibility to access the full title (e.g. via accessible tooltip) or to remove the ellipse behavior:

  white-space: nowrap;  
  overflow: hidden;  
  text-overflow: ellipsis;

to:

  white-space: normal;

See the discussion in the Gin issue for recommendations from @mgifford and @rkoller.

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet