Display the "Verify your other sessions" modal at every startup

[manuroe]

To advertise/force the user to have a full list of verified devices.
This must be displayed only if cross-signing state is "it can cross-sign".

The review button should open Settings > Security > MY SESSIONS

https://www.figma.com/file/wwqBo5oAFfk8XKmtd2YaIs/Cross-signing?node-id=4645%3A27296

As we display only one modal at a time :/. This modal has an higher priority than the modal for new detected signin.