Implement BatchPoster for Inventory (FOLIO JSON) records #62
Description
folio_migration_tools has functionality that allows the user push batches of records into FOLIO from a file containing lines of FOLIO JSON objects. For Inventory records (instances, holdings, and items), it makes use of the batch-sync endpoints in mod-inventory-storage, including upsert functionality. This capability has significant utility outside the data migration context, as well, so we should look at moving it from folio_migration_tools into folio_data_import.