Install redirections to hifis.net

Content from aai.helmholtz.de is to be has been migrated to hifis.net. Here: Remove doubled content, install cross-linkings, etc.

• Forward landing page / to hifis.net/aai/
• Forward all posts
• Forward /policies
• Forward /concept(s)
• Forward /howto
• Forward /faq to specific subsection (to-be-integrated) in hifis.net/faq
• Forward /news
• Clean errors
• Clean up unneeded stuff 👉 !30

---

Related:

• hifis/overall/hifis.net#231 (comment 1406112)
• hifis/overall/hifis.net!512 (merged)