Add new job to set the GPT partition UUID

The GPT partition layout supports unique GUID partitions.

The CLI sfdisk sets the partition UUID using the option --part-uuid.
See the examples below:

$ cat <<EOF | sfdisk disk.img
label: gpt
type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, size=64M
type=0FC63DAF-8483-4772-8E79-3D69D8477DE4
EOF
(...)

$ sfdisk --dump disk.img
(...)
disk.img1 : start= 2048, size= 131072, type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, uuid=BBE806BB-8567-A843-9FF5-9B6B35D2908E
disk.img2 : start= 133120, size= 1963999, type=0FC63DAF-8483-4772-8E79-3D69D8477DE4, uuid=7DB39F08-C138-664B-B38E-ED2DEB549AA6

$ sfdisk --part-uuid disk.img 1 00000000^C000-0000-0000-000000000000
(...)

$ sfdisk --part-uuid disk.img 2 11111111-1111-1111-1111-111111111111
(...)

$ sfdisk --dump disk.img
(...)
disk.img1 : start= 2048, size= 131072, type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, uuid=00000000-0000-0000-0000-000000000000
disk.img2 : start= 133120, size= 1963999, type=0FC63DAF-8483-4772-8E79-3D69D8477DE4, uuid=11111111-1111-1111-1111-111111111111

This commit introduces the new job set-partition-uuid that is used in
the new-operation to set the UUID of the partition. The job uses the
newly introduced method setPartitionUUID that is implemented by the
sfdisk and dummy backends.

Note: This is a copypaste of what was done for GTP partition label in
commit f585f6c (Add new job to set the GPT partition label).