Updates to people UI/UX

[lucastbelem]

• [x] Add error messages to user when they don't fill all of the fields (only fields that don't need to be filled are email and phone)
• [x] Make the modal a 2-step screen.
• [x] Part 1 is everything above "Teams".
• [x] Change "Save" button to "Next". This button effectively creates the user.
• [x] Part 2 is everything from "Teams" down.
• [x] Make button "save".