Support new boot override setting design

Add support for the new boot override setting design that was
pushed in this commit:
"phosphor-settings-manager: redesign boot setting override feature"
(https://gerrit.openbmc-project.xyz/c/openbmc/openbmc/+/44226)
The new design not only simplifies boot override settings handling,
but also adds support for the invalidation of "boot flags valid"
bit.

Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
Change-Id: I3231190ec5385d33bb0eac61540513c2666fe023
1 file changed