[firebase_ui] firebase ui package for flutter

[NoamDev]

Is your feature request related to a problem? Please describe.
Creating ui for for example phone registration feels like inventing the wheel, it requires work and widgets to have an authentication ui in the level of firebase ui.

Describe the solution you'd like
I would like a package for flutter that would be like firebase ui, for me, I think firebase ui for auth would be enough, at least for start

Additional context
I believe that is shouldn't be a plugin that wraps firebase ui for android and ios, because platform views aren't stable enough and, in general, it makes more sense to me to use the wonderful widgets system flutter provides.