Figure out what to do with Logged in E-file users emails

[BryceStevenWilley]

We ask for it in the interview, but if they're already logged in, they shouldn't need to give it again. Could either:

• use the logged in one as default, which lets them edit users[0].email
• use it automatically (could still mention that this email is being used)

[BryceStevenWilley]

Note: both of these are present in efiling_integration.yml: default is made from a function called contact_info_with_defaults(), and the email has a code block that sets the email to the logged in email if the current user is the filer.

• Using that code block only works if the person isn't an attorney, and does open up the point that the attorney would need to enter the user's email anyway. So entering the email should be the way we do it.
• Using the defaults function would require making sure we use mobile_number or phone_number when necessary, instead of just phone number. Doable, but just confusing, don't remember what our question library approach was for multiple phone numbers.