Migrate support for microcode update to GRUB
Issue migrated from deprecated booting repository: https://booting.oniroproject.org/distro/oniro/-/issues/247. Related to: https://booting.oniroproject.org/distro/oniro/-/merge_requests/539
Inside https://booting.oniroproject.org/distro/oniro/-/merge_requests/539 we are switching to GRUB on Qemu and SECO x86 based platforms. In the case of SECO x86 system, we are switching from sd-boot and the configuration file which supported updating the CPU microcode early on system startup.
We want to restore this feature to the GRUB-based images at the earliest opportunity.