This commit also refactors OAuth2 client properties. With
the added support for authorization_code clients, client
registrations are now divided into `login` and `authorization_code`.
An environment post processor is used for backward compatibility with
old Open ID Connect login clients.
Closes gh-13812
Until the fix for JDK-8209506 [1] is available in Java 11 builds,
SSL connections to services using Google's SSL certificate do not work
due to a lack of trust. This affects both our OAuth2 client samples
which were using https://accounts.google.com as an OpenID Connect
provider.
This commit switches the two samples to use Yahoo in place of Google.
See gh-14028
[1] https://bugs.openjdk.java.net/browse/JDK-8209506
