Dependency not set in config when button is enabled.

Problem/Motivation

When the buttons that this module implements are added to an editor, the resulting config does not set a dependency, which can result in problems in distributions or config exports.

Steps to reproduce

- Enable the module and add the buttons as noted on the project page
- Export config
- Observe editor.editor.full_html.yml (or your own format's config) contains entries for fontColor, fontBackgroundColor but does not have a dependency on ckeditor5_font.

Exporting this code and importing it (via Features or a Profile, without core.extension.yml will not properly enable this module, and will result in an error on the editor config page (/admin/config/content/formats/manage/full_html):

In the console:

Uncaught TypeError: Cannot read properties of undefined (reading 'id')

On the screen:

Proposed resolution

When the provided buttons are enabled in the toolbar, the editor config should set a dependency on this module.

Remaining tasks

Do it.

User interface changes

API changes

Data model changes