Excel/CSV export should allow selection of delimiter

[smutniak]

Multiple subjects are rendered with a comma delimiter which is ambiguous for CSV based exports - its not clear if this is a list of subjects or each subject is its own column

[smutniak]

Will resolve zendesk ticket 17320

[smutniak]

Given that we are looking at V5 in the next year we may want to create a hardcoded delimiter for subjects which is not ',' such as '|' in model/packager/ExcelPackager.java

The alternative is to add controls to controllers/submission/submissionListController.js and views/modals/submissions/batchDownloadExport.html etc.