Merge branch '2023-09-12-gpt-improvements' into next

Bring in two series to improve GPT support.  For the first series from
Joshua:
Adds several improvements and additions to the gpt command processing,
specifically (although not exclusively) for the purpose of supporting
"ping-pong" booting when doing A/B boot partitions with u-boot itself.

In this mechanism, u-boot must boot up, and then check if the correct
boot partition is active, and if not switch the GPT partition table to
the other boot partition and reboot to activate the other u-boot.

In order to facilitate this, the gpt command needs to be better at
preserving entry attributes when manipulating the partition table. It
also learns two new commands, one which can swap the order of partitions
in the table, and another that lets it change which partitions have the
bootable flag.

For the second series from Heinrich:

To partition a block device the partition type GUIDs are needed but
'gpt read' does not provide these. Add the missing parts.

There is some overlap in these two series but I believe I have merged
things correctly.