v5.19.1 Challenge Fixes

API

• Fix: Don't allow non admin users to assign "Habitica Official" category to Challenges (@phillipthelen)
• Fix: Automatically set legacy official field when habitica_official category is assigned to a Challenge (@phillipthelen)
• Chore: Locale files updated (@weblate)

Client

• Chore: Remove link to outdated multilingual news wiki from Bailey modal (@SabreCat)