Use JS array instead of JSON object when creating lists of items for quick actions, respect all pages

Remove rspamd size limit

This ensures that the spam and antivirus filters cannot be evaded by making the message large enough.
Rspamd does not need a size limit on its own (e.g. for DoS protection) as Postfix already has a size limit (message_size_limit).

Fix CalDAV/CardDAV URLs displayed in SOGo web interface when used behind reverse proxy

Fixes and warnings added to "First Steps" step two and three