Fragment link pointing to <textarea> should be redirected to CKEditor 5 instance when CKEditor 5 replaced that textarea

Problem/Motivation

See #2729663: Fragment link pointing to <textarea> should be redirected to CKEditor instance when CKEditor replaced that textarea. Same problem with CKEditor 5.

Steps to reproduce

Proposed resolution

Remaining tasks

1. Port test coverage from \Drupal\Tests\ckeditor\FunctionalJavascript\CKEditorIntegrationTest::testFragmentLink().
2. Add fix.

User interface changes

API changes

Data model changes