The automatic rescan of the partition table is triggered by udevd. The
udev rule that causes this is not present on the cut-down system that
runs the classic installer.

This prevents disks/partitions being auto-mounted by e.g. Thunar
when drakdisk probes the disks or makes changes, which can lead
to disk corruption.

It's required by x11-driver-video, and removing that orphans all
the other required x11 video driver packages.

This relaxes the rules in fs::any::is_boot_bios_part_needed to allow
the BIOS boot partition to be located on any disk, not just the disk
containing the root partition. It also ensures that a BIOS boot
partition is never forcibly required in a system with non-GPT disks.

This adds a specific subroutine, fsedit::auto_allocate_boot_bios_parts
that detects if a BIOS boot partition is needed and allocates it if so.
This allows us to relax the rules in fs::any::is_boot_bios_part_needed
to allow the user to manually allocate the BIOS boot partition on a
different device if they so wish.

In the normal case that installation is confined to a single disk,
this will allocate a single BIOS boot partition on that disk. In
the rare case that installation is spread over multiple disks, it
will allocate a BIOS boot partition on every disk. Given that the
BIOS boot partitions are very small and that this is not a normal
use case (see mga#16055), this seems an acceptable quirk - and does
allow the user to then choose any disk when installing the boot
loader.

The following patches want to use it outside the partition_table module.