Describe your changes

This PR adds the following changes:

• migrated setup keys from plain text to hashed format in the database
• allows custom expiration time for setup keys. There is no limit anymore, it even allows not expiring keys
• add delete endpoint for setup keys

Issue ticket number and link

Checklist

• Is it a bug fix
• Is a typo/documentation fix
• Is a feature enhancement
• It is a refactor
• Created tests that fail without the change (if possible)
• Extended the README / documentation, if necessary