Notify users when 2FA is disabled on their account in case something was
fishy about it. This notification is a "system" notification that will
be displayed in the web UI and sent over email. It can't be opted out of
as a preference.
The notification links to Special:Preferences, where users can see their
2FA status and re-enable it if they want. A secondary help link goes to
[[mw:Help:Two-factor authentication]], but can be overridden by
adjusting the "oathauth-notifications-disable-helplink" message. The
notification text is different based on whether the user disabled 2FA on
their own, or an admin used the special page or a maint script to do it.
On Wikimedia wikis, we'll use the WikimediaMessages extension to
customize the messages.
The Echo (Notifications) extension is not required, this will gracefully
do nothing if it's not enabled.
Bug: T210075
Bug: T210963
Change-Id: I99077ea082b8483cc4fd77573a0d00fa98201f15
