Add confirm/discard option and change log to Priority/Schedule draggable changes

When viewing content or looking at content in a schedule view, content can be dragged around to adjust the schedule or priority. With many collaborators and several content pieces this means unintentional changes to content might be done without knowledge or consent and impact targeting being set up or content becoming visible accidentally.

There should be a way to confirm or discard draggable changes in these views (content list and scheduler) as well as a way to view a log of changes to priority.