Subscriber User can zero out remaining budget carryover when selecting "End Contract" to Pause campaigns

When user clicks the "End Contract" button or Schedules "End Date" and selects the STOP SPENDING option, they can choose to have the Budget Carryover balance to be eliminated, i.e. Zeroed Out.

After the order is processed, the order status is set to PAUSED. The carryover balance will be set to zero. (This should be done as soon as possible and it is recognized that it might not be until the next day when ABU runs).

The amount of the budget carryover balance that was eliminated must be stored for the merchant along with the date it was eliminated so that it is retrievable at a subsequent time by either Tech Ops or automated internal report. Displaying this information in the UI is nice to have but not a minimum requirement.

We will punt on the edge case when the user chooses to Zero out the Carryover Balance and then Deploys an Active order before ABU zeroes out the balance.

User can track the history of this change (who and when) just like any other order change.