libfdisk: (script) support shortcuts in the type= field

libfdisk: (script) support shortcuts in the type= field

The unnamed-field format supports partition type shortcuts:

	",1MiB,L'

but for named-field format it requires full type:

 (mbr)	"size=1MiB,type=83"
 (gpt)  "size=1MiB,type=0FC63DAF-8483-4772-8E79-3D69D8477DE4"

This patch implements type shortcuts also for named-field format:

	"size=1MiB,type=L"

to make it more user-friendly and unified.

Addresses: https://github.com/karelzak/util-linux/issues/837
Signed-off-by: Karel Zak <kzak@redhat.com>