Regression: FileVideoFormatter Manage display page crashes when dimensions are blank

Problem/Motivation

Steps to reproduce

Proposed resolution

Remaining tasks

Regression details

Drupal 11.4.5 regressed the nullable FileVideoFormatter dimension behavior delivered by #3245446. Saving blank Width and Height correctly stores NULL and omits the video attributes, but the Manage display page then crashes while rendering the formatter summary.

Steps to reproduce

1. Configure a Video media field to use FileVideoFormatter.
2. Clear Width and Height, then save the formatter settings.
3. Reload the Manage display page.

Expected: the page loads and the settings summary omits unset dimensions.

Actual: TypeError: Drupal\Component\Utility\Html::escape(): Argument #1 ($text) must be of type string, null given.

Proposed resolution

FileVideoFormatter::settingsSummary() should only add Width and Height summary lines when their values are set, consistent with the settings form and rendering behavior. Add functional regression coverage for the both-unset case.

Remaining tasks

- Create merge request.
- Review.

No API or data-model changes.

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet