Bug 405557

SUMMARY
Allow rebooting into specific entry from leave options

ADDITIONAL INFORMATION

Even single-boot systems have memtest and rescue boot entries, so this is not exclusive to multi-boot systems.
This also should blend in well with the new 'reboot into UEFI' option.
I think of a menu in Kickoff in Leave tab that opens when you either hover over "Reboot" for some time or after right-clicking there comes a pop-up? Or any other way you think would be good. (Maybe a new entry in leave options)

The backend would be 'grub-reboot #' command
Currently to achieve such a reboot, one has to open up a terminal and type 'sudo grub-reboot #' - where # is the number of right boot entry, so the user must know it beforehand.

This solution within Kickoff(Kicker as well?) could be smarter - scraping data from GRUB config files to inform user which entry corresponds with given number, so there could be a sub-menu with a list of boot entries, like:
- Neon
- memtest
- UEFI
- Windows
- Androidx86
- Other-distros..
- etc.

Summing up, users would not need to watch for grub menu during boot, and waste attention not to miss it (good luck if it is hidden or has 2s timeout). It is not only handy, comfortable feature, but it also allows for better boot experience, as with it, there is no need to show GRUB menu at boot time at all! (unless you press e.g. shift, or some error happened yielding 30s timeout, which grub does automatically for us)