New creates a new OpenID Connect provider, and sets up important connection details.

NewCustomisedURL is similar to New(...) but can be used to set custom URLs hence omit the auto-discovery step.

NewNamed is similar to New(...) but can be used to set a custom name for the provider in order to use multiple OIDC providers.

Unused but available to set in Provider claims.

Provider is the implementation of `goth.Provider` for accessing OpenID Connect provider.

Session stores data during the auth process with the OpenID Connect provider.