Introduced EditorUI#update event

[oskarwrobel]

Suggested merge commit message (convention)

Feature: Introduced EditorUI#update event. Closes ckeditor/ckeditor5#2890.

BREAKING CHANGE: EditorUI is not an interface anymore. It is a class now.

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CI

• https://github.com/ckeditor/ckeditor5/tree/t/ckeditor5-core/130

Requires

Editors

• Used EditorUI as a ClassicEditorUI parent class. ckeditor5-editor-classic#74
• Used EditorUI as an InlineEditorUI parent class. ckeditor5-editor-inline#40
• Used EditorUI as a BalloonEditorUI parent class. ckeditor5-editor-balloon#21
• Used EditorUI as a DecoupledEditorUI parent class. ckeditor5-editor-decoupled#16

Plugins

• Used UI#update event instead of View#render to attach the UI components. ckeditor5-link#197
• Used UI#update event instead of View#render to attach table UI. ckeditor5-table#78
• Used UI#update event instead of View#render to attach the UI components. ckeditor5-ui#416
• Used UI#update event instead of View#render to attach the UI components. ckeditor5-image#215

[oleq]

@Mgsy Can you check out the constellation? The changes affect almost every feature and there could be serious regressions.

[Mgsy]

The link balloon 'jumps' after applying the link:

After changing throttling time from 50ms to 10ms in this line, everything works fine.

[oskarwrobel]

The link balloon 'jumps' after applying the link:

Done.

[coveralls]

Coverage remained the same at 100.0% when pulling 051d76b on t/130 into 7dda00a on master.

[Mgsy]

LGTM.