test: obj_defrag_advanced

Create the most fragmented pool possible and try to defragment it.

- allocate multiple copies of graph nodes
    - nodes in each copy are randomly ordered
- pick one copy of each node and free all others
    - generating possibly most fragmented pmemobj pool
- store PMEMoids to other nodes within each node (the edges)
- defragment the pmemobj pool
- verify the result

Co-authored-by: Oksana Salyk <oksana.salyk@intel.com>