Upgrade dependencies and adjust the code to the latest changes in CKE 5

[pomek]

I tried to upgrade dependencies defined in the yarn.lock file in #60 but unfortunately, it ends with the duplicated modules error.

I thought that changing numbers in pkg.json will be enough:

{
    "@ckeditor/ckeditor5-basic-styles": "^11.1.4",
    "@ckeditor/ckeditor5-build-decoupled-document": "^12.4.0",
    "@ckeditor/ckeditor5-core": "^12.3.0",
    "@ckeditor/ckeditor5-paragraph": "^11.0.5",
    "@ckeditor/ckeditor5-ui": "^14.0.0",
    "@ckeditor/ckeditor5-utils": "^14.0.0"
}

But it's more complicated and after that, 12 tests fail (related to RTL changes) and 50% of the test log is filled by non-related console logs.

[oleq]

This has been fixed around here #46 (commits).