Display the base device as well as the encrypted device in blockdev list when the device is encrypted

[mulkieran]

Something like /dev/dm-4 (on /dev/sdb). This will be in two parts:

1. Expose the information over the D-Bus. Should this be in a separate property, or in the same, multi-part property. PhysicalPath property is already exposed over the D-Bus. So this is purely a CLI issue.
2. Adapt the CLI to use the information.
   We can drop in the subissues later.

[drckeefe]

Could this be flipped?
/dev/sdb (/dev/dm-4)
Displaying the base device and putting the encrypted device in ()s?

[drckeefe]

Output of stratis blockdev list with base devs in ()s

Pool Name   Device Node   		Physical Size   Tier
nova        /dev/dm-6 (/dev/vdc)        19.98 GiB   	Data
nova        /dev/dm-7 (/dev/vdd)        19.98 GiB   	Data
nova        /dev/dm-8 (/dev/vde) 	19.98 GiB   	Data
vanilla     /dev/vdb           		20 GiB      	Data

Output of stratis blockdev list with encrypted device in ()s

Pool Name   Device Node   		Physical Size   Tier
nova        /dev/vdc  (/dev/dm-6)       19.98 GiB   	Data
nova        /dev/vdd  (/dev/dm-7)       19.98 GiB   	Data
nova        /dev/vde  (/dev/dm-8)	19.98 GiB   	Data
vanilla     /dev/vdb           		 20 GiB      	Data

In the second output all the base devices that where used in the creation of the pool are listed in the same column, which
to me seems more understandable than the first version of the output.