[GYR1-843] Add consents to the DIY flow - email portions

[spompea-cfa]

Link to Jira issue

• https://codeforamerica.atlassian.net/browse/GYR1-843

Is PM acceptance required? (delete one)

• Yes - don't merge until JIRA issue is accepted!

What was done?

GYR1-843 has been split a couple times; the overall goal has been to enhance the
DIY flow (namespace DIY::) like so:

• GYR1-915 update consent language (main and DIY flows)
• GYR1-843 Add Notification Preference page with Email checkbox (DIY)
• GYR1-??? Similar to above but for cell phones (SMS) (DIY)

The new screens should look like their counterparts in the main VITA intake flow
(namespace Questions::).

Regarding SMS/texts:

• Here, unlike the main intake flow, there are no email or sms/text verification steps.
• An SMS confirmation message might still be sent (future ticket) TBD

So, at this point, for this ticket, the main bits are:

• supporting underlying code (e.g., in the DIY base_controller, etc.)
• notification_preference controller, with just an 'Email' checkbox (the 'Text'
  checkbox is hidden for now)
• the new email_address controller -- a form to collect an email address.

A comment about an oddity that you might notice here: in addition to the new
screen added in this PR, the initial DIY screen ("File Yourself") also already
collects an email address (and, also, email_address is a required field -- a
legacy config). A follow-up ticket, 877, will remove/change both of these legacy
aspects.

How to test?

Follow this clickpath:

• home page
• click File Myself Get Started
• click Yes I Qualify
• Fill out the File Yourself form) and submit
• Choose the 'Email' checkbox and submit
• Fill out the Email Address form and subit
• Ensure you successfully arrive at the "Get support while you file on your
  own!" page.

Screenshots (for visual changes)

[github-actions]

Heroku app: https://gyr-review-app-6173-d33e594e8023.herokuapp.com/
View logs: heroku logs --app gyr-review-app-6173 (optionally add --tail)

[tahsinaislam]

I think you can add before_action :require_diy_intake like the ContinueToFsaController so it redirects to the first question

[spompea-cfa]

ok great thanks @tahsinaislam !

[tahsinaislam]

lgtm!