💡 onFocus & onBlur events

I'm using a combination of a few libraries where some has keyboard listeners. The listeners are also active when focused on the editor. I don't want to give up on this feature. Ideally, I would toggle it off when `editorjs` is in focus and toggle it back on when `editorjs` is blurred.

I believe `onBlur` PR was already merged. Here is the PR: [https://github.com/codex-team/editor.js/pull/1224](url). Although this isn't reflected on the docs. Was it removed?

It would be useful in such specific scenarios to have these events.

Thanks.