Redirects that come to the site end up in 404

This has been already reported in 🐛 Links for Drupal 8 documentation are wrongly redirected Closed: duplicate .

I've put together some code that will try to match a non-existent branch to the closest one in the same major version. This means that links ending in 8.2.x, 8.5.x, 8.8.x will be redirected to the same URL but using 8.9.x, which is the only Drupal 8 branch setup in the site.

I've put this together in between flight changes, so I'm not going to try to deploy until I'm fully back home, but wanted to put the code here for review and for the CI to run.

Code and the new tests that test it are passing now. I'm merging this and will deploy it to the site shortly for a full test.

The fix has been deployed to production. When a branch does not exist in a link, it will try to find the next major branch and redirect there.

eg:
- https://api.drupal.org/api/drupal/core%21modules%21ckeditor5%21ckeditor5... ===> 11.x
- https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Component%21Util... ===> 8.9.x

Automatically closed - issue fixed for 2 weeks with no activity.