OAuth2LoginAuthenticationProvider uses OAuth2AuthorizationCodeAuthenticationProvider

[jgrandja]

The OAuth2LoginAuthenticationProvider performs most of the same logic that exists in OAuth2AuthorizationCodeAuthenticationProvider. We should re-factor to allow for reuse.

[rwinch]

Related to this is that OAuth2LoginAuthenticationToken could extend OAuth2AuthorizationCodeAuthenticationToken which seems logical and would allow the existing OAuth2 Log In code to be passive.