feat(shed): actor state diff stats

[rvagg]

lotus-shed stat-actor \
  --tipset bafy2bzacecykodiotdljp4s23iysjc5i6475m2ag5ixjenrotqgrmnz77zscs,bafy2bzacecbydffjzfoxjunklbtckxayjl442tlewakj7teupzjdcu6i6iz6e \
  --diff-tipset bafy2bzacedzezzfig27gaohijy7tx5vgb77vih4ri3vtej5gxjbne7v6o3qfs,bafy2bzaceab7d56jwldxtye3k5egh476kk6gzvdukncdizmkw6ssssa5znqdg \
  f08403 | jq

Extends stat-actor, which prints DAG stats for an actor, and adds a --diff-tipset flag that lets you specify a second tipset that you want to diff the stats against. Instead of totals, the output will be just the mutated diff between the two (i.e. the unique blocks in the actor's DAG).

[rvagg]

well that works 👌