Remove reboot from UI

[mrpalide]

Feature description
Based on #1640 and #1641 we have some issue on current reboot bottom, two issue on different OS.
As I had talk with @0pcom, in boards we use systemd services, so just shutdown the visor work as reboot.
And on desktops, means Windows, Mac and Linux we don't needs reboot visor functionality, so we can just keep shutdown bottom there that its PR availabe at #1642
So we just want add shutdown API for #1642 and remove reboot bottom there. So we should remove reboot and restart command from skywire-cli too.