Zendesk SSO

Closes minds#2612 (closed)

Dependants

• Front front!1565 (merged)
• Helm helm-charts!50 (merged)

Depends on

Zendesk admin panel configuration https://gitlab.com/minds/engine/-/issues/2033

Summary

These changes replace the existing helpdesk with Zendesk.

Testing

To test, login and hit Help in the topbar dropdown - try changing emails and firing up new accounts etc.

Regression Scope

Changes to our system are mostly additive - redirect at /help and the dropdown button are behind a feature flag.