Function create_role_update_event 

pub fn create_role_update_event<T>(
    member: VerifyingKey,
    role: GroupRole,
) -> GroupActivityEvent<T>

Create a role update event TODO: This function is temporarily disabled due to IdentityRef expecting Ed25519 keys while the message system now uses ML-DSA keys. This needs to be updated when IdentityRef is migrated to ML-DSA.