Add "External Page" Option for Page Navigation in Ideas Portal

To better delineate between the purpose of idea submission and support requests, it would be useful if we could add a "Contact Support" link to page navigation in the idea's portal nav bar.

As such, we will need a mechanism by which we can designate a page as "External" pointing to an external source via web address or mailto address (e.g. https://widgets.com/support or mailto:support@widgets.com) that people can click to be directed to it in a new tab.