This mirrors a similar side fix for the API server authenticator.
Don't trim the issuer URL provided by the user since OpenID Connect
mandates that this URL exactly matches the URL returned by the
issuer during discovery.
Not test updates since this is already tested by the go-oidc client
package.
See: https://openid.net/specs/openid-connect-discovery-1_0.html#ProviderConfigurationValidation
* Use an interface for OIDC Client, so that we're testing the behavior
of the client, not the go-oidc package itself
* add backoff and retry when server rejects token
This commit handles:
* Passing ID Token as Bearer token
* Refreshing of tokens using refresh-tokens
* Persisting refreshed tokens
* ability to add arbitrary extra scopes via config
* this is what enables the cross-client/azp stuff
