Issue #3030651 by jedihe, pfrilling: Support URL-initiated Log-in through Provider

openid_connect.routing.yml

src/Controller/OpenIDConnectRedirectController.php

src/OpenIDConnectSession.php

src/OpenIDConnectSessionInterface.php

...lugin/OpenIDConnectClient/OpenIDConnectFacebookClient.php

src/Plugin/OpenIDConnectClient/OpenIDConnectGithubClient.php

...lugin/OpenIDConnectClient/OpenIDConnectLinkedinClient.php

src/Plugin/OpenIDConnectClientBase.php

src/Plugin/OpenIDConnectClientInterface.php