Reflect layout changes to the object store

[metazool]

Recent updates to the annotation half of this project include changes to the layout of the object store; so the scripts that create an intake index and read from it no longer work as intended.

Needs a small set of changes to reflect the different locations (separate buckets per-site, per-instrument) and write a shared index in the intake part.

Also needs lightweight documentation of the intake approach and its (potential, mixed) benefits - see also #4 for a discussion of how to slowly introduce a more standards-oriented approach (discoverability, reusability, all the FAIR things)

[metazool]

See also the connected issue in the internal cyto-ML project around embedding more metadata in the EXIF headers of the single images during the preprocessing (lon/lat, date, depth, other?)

[metazool]

See #18