Bug 496317

This is a minor feature request: In the reboot countdown screen, it would be very comfortable if under the "Restart Now" and "Cancel" there would be an "Advanced" dropdown that, when clicked, pauses the countdown and prompts what to reboot into:
- The default would be to "Restart normally" that just restarts as it always does,
- If the system boots in UEFI mode, "Enter UEFI setup screen" to get into the UEFI setup (like System Settings -> Session -> Desktop Session -> After next restart: Enter UEFI setup screen checkbox, just more convenient),
- If the system boots from a supported bootloader and its userspace tooling is present, a list of boot options normally presented in the boot menu. For example, systemd-boot offers a plain, single-level list of boot options listable with `bootctl list --json pretty`, which then you can boot into once with `bootctl set-oneshot <ID>`. The options presented in the menu depend on what the user has available, for example "Arch Linux (linux-lts)", "Windows 11", "EFI Shell", and so on.