osbuild: set partition name (label) in partition definitions

This will make the partitions get a partition label, which we rely
on. See coreos/fedora-coreos-config#2704 (comment)

Author: dustymabe

src/coreos.osbuild.mpp.yaml

@@ -17,22 +17,26 @@ mpp-define-image:
     label: gpt
     partitions:
       - id: BIOS-BOOT
+        name: BIOS-BOOT
         type: 21686148-6449-6E6F-744E-656564454649
         bootable: true
         uuid: FAC7F1FB-3E8D-4137-A512-961DE09A5549
         size:
           mpp-format-int: "{bios_boot_size_mb * 1024 * 1024 / sector_size}"
       - id: EFI-SYSTEM
+        name: EFI-SYSTEM
         type: C12A7328-F81F-11D2-BA4B-00A0C93EC93B
         uuid: 68B2905B-DF3E-4FB3-80FA-49D1E773AA33
         size:
           mpp-format-int: "{efi_system_size_mb * 1024 * 1024 / sector_size}"
       - id: boot
+        name: boot
         type: 0FC63DAF-8483-4772-8E79-3D69D8477DE4
         uuid: 61B2905B-DF3E-4FB3-80FA-49D1E773AA32
         size:
           mpp-format-int: "{boot_size_mb * 1024 * 1024 / sector_size}"
       - id: root
+        name: root
         type: 0FC63DAF-8483-4772-8E79-3D69D8477DE4
         uuid: CA7D7CCB-63ED-4C53-861C-1742536059CC
         size: