feat: [WIP] 🍰 Validate Group Name Etc. In Backend

Created by: Tirokk

🍰 Pull Request

I do this again in new PR #5662 , because of to much changes in the master

Validate group name etc in backend.

Issues

• fixes #5425
• relates #5059 (closed)

Todo

• rename:
  • description → groupDescription
  • descriptionExcerpt → groupDescriptionExcerpt
  • DESCRIPTION_EXCERPT_HTML_LENGTH → GROUPDESCRIPTION_EXCERPT_HTML_LENGTH
• has the goal a maximum?
  • no I think
• move the backend/scr/db/graphql folder out of the db folder one folder level higher that it fits together with #5253
  • after merge of #5380 this has to be done or fixed again
• have all fields be HTML saniticed which will be displayed in the DOM?