Refactor into more lightweight service to be deployed not only on drogon

Would require review and redesign of some operations so they would not require maintaining local copy of all dandisets and zarrs but would retain only very lean "status" DB (json file) with timestamps per each dandiset and zarr repository so whenever update detected in the archive necessary components would be cloned, updated, pushed, removed locally.

Possible related issue
- last-modified is still not updated in the archive for some changes (TODO: refs here)