Change auth for backend to SSO

[AlanBreck]

Describe the problem

cc @kdenhartog

Describe the proposed solution

cc @kdenhartog

Importance

Nice to have

Additional Information

No response

[kdenhartog]

We came across this today as @AlanBreck was walking me through the merch store. At the moment admin access is managed via a username and password without 2FA required (that might be configurable). Moving this to SSO would align it with our authentication practices and simply the usage of this since all people who will be accessing this admin panel will have SSO access.