libblkid: Add scoutfs filesystem.

libblkid: Add scoutfs filesystem.

The scoutfs filesystem is maintained out-of-tree, but current enough
that we want to submit it for inclusion in libblkid - there's a few
users out there that would benefit from being able to have lsblk aid in
diagnosing and identifying.

For more information about scoutfs, visit the github page here:
   https://github.com/versity/scoutfs

Test images are provided for both data and meta devices. These were
taken from validation samples.

The wiper is set to only wipe a minute part of the filesystem -
basically only the superblock. This is adequately destructive.

Signed-off-by: Auke Kok <auke.kok@versity.com>