Implement free-space partition replace install

This reverts commit fc4a8b86.

This way the KPMcore libpartedbackend scanner won't filter out Parted
devices of type UNKNOWN.
CAL-349

Enable support for 32bit UEFI systems with Grub

Read the UEFI bitness exposed to the file system and install the correct
variant of Grub, depending on the UEFI bitness.

CAL-359 #close

Also remove outstanding SetPartFlagsJobs when deleting a new partition.