Fix realtime edited text for issues

What does this MR do?

EE port: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1917

⚠ The target branch is 9-2-stable because this regression involves 2 fixes as the 9.2 and 9.3 codebases are significantly different. ⚠

Adds edited component for the issue_show vue app. This component will render the Edited [x time ago] by [user's name] and keep it up to date with realtime_changes data.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/32220