Add device path to bcachefs show-super

[Managor]

To make sure I have formatted and labeled the RAID correctly I would like to be able to cross-reference the labels and drive paths. Currently I wasn't able to find any way to make sure that my /dev/sda was with a hdd label unless I do cat and ls tricks in /sys/fs/bcachefs/UUID/dev-{0..3}/
EDIT: or cross-reference blkid with bcachefs show-super
EDIT2: Apparently the drive is visible in bcachefs fs usage on top of the device data column, it just averted my eyes. If there is no intention to put the full drive path in show-super please feel free to close the issue.

[presto8]

I agree, it would be very useful to have the info in show-super. Indeed, it is available in fs usage, but that requires the filesystem to be mounted. Having it available in show-super allows it to be visible before mounting.