Create email consent page

[mathjazz]

Fix #3219: Adds Email consent screen as per the spec for existing and new users.

The patch is deployed to stage:
https://mozilla-pontoon-staging.herokuapp.com/

[mathjazz]

@bcolsson Could you please test this on stage and let me know if there are any changes needed to the functionality?

After you dismiss the email consent screen, you can enable it again by clearing the "Email consent dismissed at" Time and Date fields for your Pontoon user.

[bcolsson]

Looks good to me.

I'm curious if we should make the header for the email consents configurable as well, but I'll leave the decision up to you.

[mathjazz]

Sorry, added missing Middleware tests:
e293e96

[eemeli]

Besides the line comments, I'm a bit concerned that the interstitial page only explains what happens if a user consents to emails, and not what happens if they choose "No, thanks". Could text about that be included?

I would expect it to say something like "If you opt out, you'll still be able to enable emails later from the settings page."

[mathjazz]

Besides the line comments, I'm a bit concerned that the interstitial page only explains what happens if a user consents to emails, and not what happens if they choose "No, thanks". Could text about that be included?

I would expect it to say something like "If you opt out, you'll still be able to enable emails later from the settings page."

Texts are part of the spec and were created together with legal, so I'll let @bcolsson comment on that.

Also for this:

The "just" is unnecessary here.

[bcolsson]

We could add it and ask legal to review the final page. I'm not sure how we'd fit something specifically pointing out what happens if they choose no with the current design, but we could add something below the privacy notice like:

You can change your email communication preferences at any time from your <a href="">settings</a> page.

[mathjazz]

We could add it and ask legal to review the final page. I'm not sure how we'd fit something specifically pointing out what happens if they choose no with the current design, but we could add something below the privacy notice like:

You can change your email communication preferences at any time from your <a href="">settings</a> page.

The sooner we ship this feature, the sooner we can start sending emails to the community. Another round of review with legal and no clear idea for the design is likely to delay this process. Let's go ahead with the patch and, if needed, file a bug for potential copy improvements.

@eemeli Do you have further requests for improvements?