fix-efivars: Rework for varstored 1.2.0-3.3

* Separate into subcommands
* Add pool scan command to scan pool variables and all VMs within
* Add NVRAM restore command
* Add fix indications
* Fix out-of-date KEK/db/dbx too, using pool variables

Signed-off-by: Tu Dinh <[email protected]>

Author: dinhngtu