Update the theme to use CKEditor 5

Problem/Motivation

Update the theme to use CKEditor 5
https://www.drupal.org/node/3259165

Steps to reproduce

1. Enable ckeditor5 and go to admin/config/content/formats and change all Text editors from CKEditor to CKEditor 5
2. Go to any field where CKEditor 5 is used (preferably the one that use Full HTML text format)

3a. Insert a Link
3b. You will see that link color is wrong and link is not underlined
3c. With this improvement applied, link has correct color and is underlined
3.d Furthermore, go to admin/appearance/settings/socialblue > Color scheme > Link color and change it - you should see the link color changed in CKEeditor as well

CKEditor4 (edit mode):

CKEditor5 (edit mode, without this improvement):

Front-end (content view, also expected result):

4a. Insert a Block Quote
4b. You will see that Block Quote style is wrong, comparing to what is rendered when you view the content
4c. With this improvement applied, Block Quote style correct
4.d Furthermore, go to admin/appearance/settings/socialblue > Color scheme > Primary color and change it - you should see the Block Quote style changed in CKEeditor as well

CKEditor4 (edit mode):

CKEditor5 (edit mode, without this improvement):

Front-end (content view, also expected result):

Proposed resolution

- Set ckeditor5-stylesheets: false to remove the warning without having to add any stylesheets.
- Apply socialblue color scheme defined in settings for link and blockquote html element in CKEditor 5.

Remaining tasks

N/A

User interface changes

N/A

API changes

N/A

Data model changes

N/A