Enhanced functionality during Idea submission for Private Idea Portal

Add a custom field to an Idea submission form to allow the submitter to choose 1 or more stakeholders from the company user list, atleast for Private Portals used internally within the company

Allow "@ mention" to be used as an option in the Idea description by the submitter, to loop in key stakeholders, atleast for Private Portal. This allows for the Idea submitter to engage others early on, without active intervention by Aha! user.