Add support for volume group with thin-pool

[aarontp]

I'm not sure how prevalent these volume types are, so I can't comment on the priority here, but here is a related bug for an unsupported LVM type: google/turbinia#790

[joachimmetz]

Is this similar to #9 ? Or is this a raid LVM configuration on a single physical volume?

[joachimmetz]

Looks like a volume group with a "thin-pool"

https://www.man7.org/linux/man-pages/man7/lvmthin.7.html

[joachimmetz]

Note to self, extend https://github.com/dfirlabs/lvm-specimens with thin-pool specimens