Allow escaping code block

What does this MR do and why?

Allow escaping code block

In content editor, allow escaping code block with right arrow key

Screenshots or screen recordings

Screen Recording 2023-05-21 at 20.31.30.mov

How to set up and validate locally

1. Enable feature flag :content_editor_on_issues.
2. Create a new issue. Click Switch to rich text to use the content editor.
3. Insert a code by pressing on the toolbar.
4. Type right arrow at the end of the code block to exit it.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #406723 (closed)