Help users know where they are

Closes #466 (closed) @jandt-desy

The breadcrumbs codex works very nicely, and is light-weight 👌

• It revealed missing landing pages, so I added them, copying the corresponding part in the services overview.
  • for cloud
  • for overall
• I didn't want to start rearranging pages so more things appear under "Overall" because we have to discuss what are "overall services" (surveys = service 🤔) and mostly because of our parallel task to rearrange the landing page anyway in #467 (closed).
• I moved the "hifisfor" pages to avoid having to make a new landing page for the 4 'HIFIS for' pages so I did redirects and moved those pages to where they belonged in the clusters, just like it was the case for cloud providers before