INDEX: need to show the annotations change count

[volkfox]

currently INDEX shows a counter for NEW annotations, but it displays nothing when flipping the "current" pointer to annotation already seen.

For example, if you flip back and forth between these two commands:

ldb index s3://ldb-public/remote/data-lakes/Stanford-dog-breeds/*/ --format infer -p base-label=“dog”
ldb index s3://ldb-public/remote/data-lakes/Stanford-dog-breeds/*/ --format infer -p base-label="cat"

the counters will not show the changes:

Data format: tensorflow-inferred

Indexing paths...

Finished indexing:
  Found data objects:        10799
  Found annotations:         10799
  New data objects:              0
  New annotations:               0
  New data object paths:         0

This is confusing because the state of the index does change and it affects dependent datasets.

The proposal is to show a combined "New/changed" annotation counter that is updated every time the "current" annotation pointer is altered in the index.