Add "Messages-Only" Role to Team Members

We’d like to extend the Team Members functionality in the Simple Mail Service dashboard to support more granular access control. Requested Feature: Introduce a new team member role that grants access only to the “Messages” page within the App Dashboard. Details: Role should restrict access to all other sections (e.g., Domains, Suppressions, Settings, etc.). Ideal for support staff, analysts, or compliance roles who only need visibility into sent messages and message status. Should be easy to assign when inviting or editing team members. Purpose / Benefit: This role improves security and usability by allowing organizations to give team members access to only the information they need — no more, no less.