Prevent field types of 'Global Rank' from being selected for a JIRA screen

Since Global Rank is a special field provided by JIRA Agile, it will not appear on JIRA issue screens - which is by design. It's still possible, though, to add it to screens and have it displayed in the Issue View. It's possible, too, to create a Post Function to update the Rank field in a transition (using e.g. the JIRA Suite Utilities add-on). The function won't work anyway, so we should prevent the field from being available in the configuration in the first place.

We should prevent or inform users when attempting to add this type of custom field to configuration settings.