2023-06-02 ECA Sprint: Send email to users of a given role

[Send email to users of a given role](https://ecaguide.org/library/simple/send_email_to_users_of_a_given_role/) In this video, we've built an ECA model to send an email to all users of a certain role. It contains a view with a contextual filter to limit the list of users to those of the given role.