Use entity based method `ForEachMountable` and `getDevices` to generate
all mounts and devices in a generic way, which then allows for mounts on
arbitrarily nested devices.
Update manifests and image info:
- New device names generated by `pathdot()` to avoid basename
collisions.
- Some partitions are generated in a different order now which changes
the order they appear in the manifest and their UUIDs.
Co-Authored-By: Christian Kellner <christian@kellner.me>
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.
