Issue Summary

JSM Form Attachment will be failed to have preview loaded or downloaded on a read only work item.

Steps to Reproduce

1. Step 1
   Attachment a form with attachment field to a work item, add a attachment
2. Step 2
   Set the work item read only (e.g. set `jira.issue.editable: false` in workflow)

Expected Results

The attachment in form attachment field could be loaded and downloaded.

Actual Results

The attachment in form attachment field could NOT be loaded and downloaded.

Workaround

Use Attachment panel in work item to view the attachments