Add a countdown to the sync with mobile page

**Describe the issue**
Support brought up that they always get tickets for the sync with mobile, but something that I don't think is very clear is that the QR code actually updates on an set interval. I had actually mentioned this to the support team and they were suprised to learn this themselves.

**Possible solution**
Add some sort of countdown or similar so it's clear that the QR code can timeout, thus prompting users to retry if it fails for any reason.

Start by locating the sync with mobile page and tracing where its QR code is displayed and refreshed. Confirm the QR code’s update interval, then make the remaining time visible so users know when it can expire and when to retry.

Written by the indexing model from the issue text.