Problem

People want to become members of a site, and site owners want a list of people who has followed.

We currently have a confusing situation where there is always a subscribe button at the top of every site.

Solution

Create a "Follow" button that replaces both Subscribe buttons.
The follow button:
- Creates a contact for the site that you follow
- Enable syncing subscription (desktop only)
- Enable notifications (future)
Once following, your button now says "Following" and is a dropdown. The dropdown allows you to:
- Toggle Syncing (desktop only)
- Toggle notifications (future)
- Unfollow - deletes contact
Everyone who has added the contact of an account will show up in the "People" tab for the site, visible from the top-level of the document.
For now, we will remove email functionality so the user doesn't have to input their email address again and again.
- In a future project, we will enable email notifications for all sites that you follow, by default. After following, you may disable notifications.
In the future (not in this project), a site owner will have a setting for "open membership"
- If the site is set to open membership, the button will say "Join"
- If open membership, the list of followers will say "Members"

No backend changes, less than a week of frontend changes.