Admins to be able to include custom message on automatic notifications when updating Workfront

[#1]

Description: Would like Admins to have the ability of adding a custom message when making changes or sharing things in Workfront that produce automatic notifications.

Why is this feature important to you: The notifications are vague and can confuse a user as to what was changed, shared, why it was done, and what they need to do, if anything. The ability to have a clarifying message would remove the confusion and the user would know right away what the purpose is and what they need to do.

How would you like the feature to work: The admin would check a box or indicate somehow that a message should be included when doing the update, change, or sharing. The admin would type the clarifying message and the notification would be sent to the user.

Current Behavior: Users get notifications and then have to reach out asking why they got it and if they need to do anything. We end up notifying the audience BEFORE the official WF notification goes out that they may get an email notification. In other words, we have to send a notification about a notification, specially if the audience is leadership. 

@HollySe @RudyHa1 @SuzyF @AnnaPu