[keycloak-user] Auth SPI being refactored in 3.0

The Authentication SPI is being refactored in 3.0. Like what happened in Keycloak 2.x and the User Storage SPI, the Authentication SPI will be refactored and improved through various 3.x releases. We'll clean up areas, rewrite certain areas, and get the SPI ready so that it can be stable and supportable for the foreseeable future. We are also doing this work so that we can support things like step-up authentication and FIDO etc. although the latter is for much later down the road. The first area that will be tackled will be the Form SPI. Regards, Bill