Add activity feed visibility options to emails and letters sent via templates

When an email or letter template is used to correspond with a student a copy automatically goes on the activity feed but you cannot limit visibility like you can on other items posted to the activity feed.  Our situation is that we have students who are teaching assistants, or work in admissions or campus life who have access to the activity feed because of those roles.  They can see things like collection letters sent to other students.  If  visibility options were available we could limit those templates to just the areas (financial aid, business office, for example) that need to see them.  Even having faculty or general staff access some of these is not best for the students involved.