LP1913458 Bucket Add/Delete Item Operations Batched

LP1913458 Bucket Add/Delete Item Operations Batched

In the record bucket administration UI, the act of adding or removing
items from a bucket are now done in batch to avoid too many parallel
requests.

These changes include new batch create/delete API calls that can operate
on any bucket type, so other UI's can be similarly batched as needed.

Signed-off-by: Bill Erickson <berickxx@gmail.com>
Signed-off-by: Jeff Davis <jdavis@sitka.bclibraries.ca>
Signed-off-by: Jane Sandberg <sandbej@linnbenton.edu>