[Roles] Click on user and change their role

[C2H6O]

Overview: We want the user to be able to click on each row, open a role picker dialog, change the role of that user, and see that change reflected in the UI.

1. Adds the role column to users
2. Adds the change role API to PGApi
3. Adds the role picker dialog
4. Adds the click listener to open role picker in UserAdapter
5. The role picker dialog changes the user's role (BROKEN!!! HELP!!!)

I used the API from:
https://developer.plangrid.com/docs/the-user-object