Resolve "Creating and restoring database snapshots"

Merge Request Checklist

Missing in this MR:

• UI: Automatic snapshot removal from the list of snapshots once deleted
• UI: Spinner for restore
• Locking updates once they are merged
• Enable 404 middleware again once it is fixed
• Implement delete_by_application so that there are no hanging snapshots once an application with snapshot is deleted
• Deleting expired snapshots should not be done with the user-based Job system, but with pure Celery task

Checklist:

• changelog.md has been updated if required
• New/updated Premium features are separated correctly in the premium folder
• The latest Chrome and Firefox have been used to test any new frontend features
• Documentation has been updated
• Quality Standards are met
• Performance: tables are still fast with 100k+ rows, 100+ field tables
• The redoc API pages have been updated for any REST API changes
• Our custom API docs are updated for changes to endpoints accessed via api tokens
• The UI/UX has been updated following UI Style Guide

Closes #141 (closed)