This patch adds a flag to `secureboot.database.Generate` to append the Microsoft UEFI secure boot DB and KEK certificates to the appropriate ESLs, in addition to complimentary command line flags. This patch also includes a copy of said Microsoft certificates. The certificates are downloaded from an official Microsoft repo. Signed-off-by: Jean-Francois Roy <jf@devklog.net> Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>