[CR-13160] Hierarchical Time Tracking View (based on Project Hierarchy)

We would dearly like to see the timesheet in workitem hierarchy order, with collapsable/expandable parent workitems.  This helps immensely those users who are, in any given week, assigned to numerous tasks across many projects.  By letting such users hide (or collapse away) whole projects to a single line, this brings into view - without having to scroll (as much) - other parts of their timesheet that they want to see or need to log hours against.