Make the cleanup command functional
Description
This MR expands the skeleton CAS cleanup command to call the functions for marking as deleted and deleting blobs that were added in other MRs, in order to implement cleanup functionality.
It also adds support for doing a "dry run" of the cleanup, which reports how many blobs will be deleted in order to clear up space.
Issues addressed
Closes #273 (closed)
Edited by Adam Coldrick