Allow Line Mangers to set Timesheet approval delegation for a period of time

[#1]

Description - It would be helpful if Line Managers could manage their own Timesheet delegation approval for a period of time.

Why is this feature important to you - It would save time for the Line manager and support staff if they could do this simple task themselves. 

How would you like the feature to work - As with work delegations, allow Line Managers to set another user to approve timesheet for a period of time and not just for timseheets that are already produced by the system. Need this to cover future timesheets for the period also.

Current Behaviour - At present the only options are to add an approver to current timesheets, change the direct report for the employee int he user profile, ask for new timesheet profile to be created or ask Admin support staff to manually create future timesheets and then set the approvers.