Force project wiki to use the admin theme

We should even change all paths to go into the same area

IF using /admin/* in the URL is not enough, this can also be enforced by

  options:
    _admin_route: TRUE

in the routing.yml, see https://drupal.stackexchange.com/questions/185266/how-to-set-admin-theme...

but I think it won't be needed. Just FYI. Let's see!

This does it, the admin theme works now. I think it is best not to meddle too much with the routes here, as we are planning to do a big routing overhaul at the end, see 📌 Refactor URLs and Names of Project Wiki related pages Active for that.

anybody → closed merge request !20

anybody → reopened merge request !20

FYI: I reverted this, as putting project wiki in help makes it barely invisible. Especially in the new Drupal 11 admin menu. We'll instead put it on the first admin menu level. So path will remain to start with /admin/ so this issue is kept fixed!

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