FIO-5508: Upgraded CKEditor to the latest version

[KirylDrutsko]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-5508

Description

Upgraded CKEditor to the latest version and made corresponding changes in formio.js

Dependencies

Use this section to list any dependent changes/PRs in other Form.io modules

How has this PR been tested?

Manual testing of used features in formio.js

Checklist:

• I have completed the above PR template
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings
• My changes include tests that prove my fix is effective (or that my feature works as intended)
• New and existing unit/integration tests pass locally with my changes
• Any dependent changes have corresponding PRs that are listed above