Move user/session information into a UserProvider rather than in redux

[jackcmeyer]

🚀 Feature Proposal

As part of the removing redux, this issue is to move user/session information into a UserProvider rather than stored in redux.

The UserProvider should follow the pattern outlined here: https://kentcdodds.com/blog/how-to-use-react-context-effectively/.

The Login component will be responsible for setting the user information and there should be a hook useUser that allows access to user information