Google SSO integration

[thekaveman]

Compiler staff working on the PeMS Admin interface may want to login via their Compiler Google Workspace account via SSO.

• Signing in with a known compiler.la account should automatically grant the user superuser

We could also look at this for members of the public that wish to create a PeMS account using an existing Google account via SSO.

• Signing in with a Google account should automatically add the user to the Public group Define groups for access control #167

[thekaveman]

Project close #218