R1:853544b54ae0

Add "JIRA Issues" field to Differential

Summary:
Ref T3687. This adds a field which allows you to link Differential Revisions to JIRA issues.

This is just about as basic as it can get, but gets the job done. The field enables itself if you have a JIRA auth provide. You enter JIRA issues in a comma-delimited format and it generates appropriate edges.

Nothing is pushed to the issues yet.

The only real rough part here is that if you commandeer a revision which is linked to issues you can't see, editing it…