Allow project admins to reference other projects within an organisation

Issue Summary

Please allow project admins to make reference to other instances within an organisation. At the moment, the only way to sync an issue between different instances is to use an app such as Backbone Issue Sync for Jira or Exalate Jira Issue Sync, Automation & More 

Whilst it is possible to use webhooks and the REST API, syncing issues between two instances of Jira is not a trivial task to manage manually.  If you are doing this via API calls between the instances it has the potential to be interrupted over the network and become out of sync very quickly.  Also, actions done out of sync at the same time can cause disruptions as well, as an exe two users on each site do two different actions at approximately the same time, whoever completed the action first will have the action completed correctly and the other will fail, and the issues could wind up in two different states on the instances.

Management and many employees are requesting the JQL Queries work across sites so it will display within Filters and Kanban boards.