Add SSO (OpenID Connect)

[ursinn]

This PR adds support for SSO using OpenID Connect

For OpenID Connect it uses the following library (added via composer)
https://github.com/jumbojett/OpenID-Connect-PHP

SSO

The SSO feature was testet againts the following Identity Providers (IdP)

• Okta (Workforce Identity Cloud, Developer Edition)
• Authentik (Open Source)
• Microsoft EntraID / Azure AD (tenant of feature sponsor)

SSO can be configured as super-administrator in the UI or via the app.yaml file

Example Okta

The following settings must be configured:

setting	value
provider_url	(Example: https://dev-0000000.okta.com/)
client_id	(client id)
client_secret	(client secret)

Example Authentik

The following settings must be configured:

setting	value
provider_url	(Example: http://server:9000/application/o/repomanager/)
authorization_endpoint	(Example: http://localhost:9000/application/o/authorize/)
client_id	(client id)
client_secret	(client secret)

app.yaml

• Allows for automation.
• Created automatically for new installations, must be created manually for existing installations.
• The settings configured in the file override the values configured via the UI.
• It is possible to use both the file and the UI for configuration.

[ursinn]

The SSO implementation and config file are ready for review.

[lbr38]

This is now merged in devel. I will take care of the CI issues and do the adjustments needed. Thanks again for your work!