Support token representing iteration identifier within config file parameters and filenames

[banerjek]

Object files created by the tools contain the iteration identifier. Since different iterations change the name of the output files, it would be helpful to simply reference the identifier within parameter/file values rather than having all input files be string literals.

For example, instead of
"iterationIdentifier": "current"

{ "name": "bibs_poster", "migrationTaskType": "BatchPoster", "objectType": "Instances", "batchSize": 500, "files": [ { "file_name": "folio_instances_current_bibs.json" } ] }

the syntax
{ "name": "bibs_poster", "migrationTaskType": "BatchPoster", "objectType": "Instances", "batchSize": 500, "files": [ { "file_name": "folio_instances_{iterationIdentifier}_bibs.json" } ] }
could be used. As number and type of files increase, this will simplify config and save time

[banerjek]

Not needed