Allow redirecting wiki directories on rename

What does this MR do and why?

Allow redirecting wiki directories on rename

Previously wiki pages would redirect on rename, but any child pages in a directory would not. This commit allows redirecting the entire tree to be redirected.

Changelog: changed

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

N/A

How to set up and validate locally

Try renaming directories in wikis. See tests for examples. Also see !150727 (merged) that added the original feature.

Feature flag: :wiki_redirection