WIP: Login mirror

mirrors !255 (closed) @jsar97 @rapl42 i continue to experiment on this branch

there is an openid connect plugin for flutter that released recently:
https://pub.dev/packages/openid_client/install

people try to do the same:
https://stackoverflow.com/questions/60814356/authenticate-flutter-app-with-keycloak-and-openid-client

Edit: 2020-12-11, this is obsolete because we're trying another method