Instead of hard coding a padding of 100 sectors for all layouts, i.e.
MBR and GTP, adjust the needed space depending on the layout: for MBR
we don't need to reserve any space at all since it does not have a
secondary header. For GTP we reserve 33 sectors, as indicated in the
UEFI specific, which allows for the header itself and up to 128 entries.
To not modify the layout of already released distributions, like RHEL
8.4 and 8.5, a new member called `ExtraPadding` is added to `Partition
Table` and then used in the corresponding layouts to preserve the
existing padding of 100.
