Accounts & devices fuse

[lleyton]

Essentially a dashboard to manage basic account settings as well as view other connected devices to this account. It would also be nice to be able to view the online state of other devices, and maybe some more advanced remote control features? (That would be in scope for another issue though.)

This would require work as a Fusebox plug, as well within the Xenon daemon to handle the authentication in the first place. For the authentication backend, we are currently planning to use Logto.