✨(feat) Migrate to CKEditor 5 + allow back Php7.4

[floviolleau]

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	yes
Deprecations?	yes
Fixed tickets	N/A
License	MIT

Hi,

This is a full rewrite to make it working with ckeditor 5. Because I still use Symfony 5.4 and Php 7.4, I allowed to install with Php 7.4

Here is an example of configuration:

# Read the documentation: https://symfony.com/doc/current/bundles/FOSCKEditorBundle/index.html
twig:
    form_themes:
        - '@FOSCKEditor/Form/ckeditor_widget.html.twig'

fos_ck_editor:
    default_config: classic_config
    powered_by: false
    configs:
        balloon_config:
            build: 'balloon'
            toolbar: { items: ['bold', 'italic', 'bulletedList', 'link' ] }
        classic_config:
            build: 'classic'
            minHeight: '212px'
#            width: '50px'
#            licenseKey: 'your-license-key',
            toolbar: { items: ['undo', 'redo', '|', 'bold', 'italic', 'bulletedList', 'link' ] }
#            ui: { poweredBy: { position: 'inside', side: 'right', label: '' } }
#            extraPlugins: ['ResizableHeight']
#            ResizableHeight: {
#                resize: false,
#                height: '500px',
#                minHeight: '100px',
#                maxHeight: '1000px'
#            }
#            style: {
#                definitions: [
#                    {
#                        name: 'Article category',
#                        element: 'h3',
#                        classes: [ 'category' ]
#                    },
#                    {
#                        name: 'Info box',
#                        element: 'p',
#                        classes: [ 'info-box' ]
#                    },
#                ]
#            }
#            template: {
#                definitions: [
#                    {
#                        title: 'The title of the template',
#                        description: 'A longer description of the template',
#                        data: '<p>Data inserted into the content</p>'
#                    }
#                ]
#            }
    styles: { '.ck.ck-editor__editable': { 'background-color': 'red' }

#    plugins:
#        ResizableHeight:
#            path: '/bundles/ckeditor5-resizableheight/'
#            filename: 'plugin.js'

Remaining tasks:

• [ ] Tests need to be changed
• [ ] Be able to download several predefined builds to be able to use different config
• [ ] Make form type working with other things than ClassicEditor. The only editor type which can be initialized on elements is the classic editor. This editor hides the passed element and inserts its own UI next to it. https://ckeditor.com/docs/ckeditor5/latest/support/error-codes.html#error-editor-wrong-element
• [ ] Make Plugins working (blockers https://ckeditor.com/docs/ckeditor5/latest/support/error-codes.html#error-ckeditor-duplicated-modules and https://github.com/ckeditor/ckeditor5/issues/14745#issuecomment-1670822989

[Nek-]

Related issue: #242