National RBAC role selection UI

Currently, for smartcard users, the Identity Agent will ask the end user to select a role to use for the current session (using the list of nationally-defined roles assigned to them by their Registration Authority). However, (a) there is no facility for them to change their role and (b) there is no role selection for end users using other authentication methods with NHS Identity. Rather, calling applications must retrieve the list of valid roles for the user and build a UI to allow the user to select a role. The scope of this feature would be for NHS Digital to build a UI for user role selection, for use with NHS Identity.