Support Configuring OAuth2 Login with `OAuth2AuthorizationRequestResolver` by publishing a Bean

[rwinch]

gh-15236 added support for configuringOAuth2AuthorizationRequestResolver for OAuth2 Client's by publishing a Bean. This is a similar feature, but for OAuth 2 Login.

NOTE: I haven't looked into this in detail, but at minimum this is not supported by OAuth2LoginConfigurer which means that oauth2Login() for servlet applications does not work.

[rwinch]

Closing in favor of the pull request gh-16381