Implement "Notify user" flag during Request Cancellation

Purpose:
To implement a "notify user" flag on the Request Cancellation confirmation modal, for use by other processes or apps, such as patron notifications

1. Scenario
   • Given a "Confirm request cancellation" modal
   • When displayed
   • Then a "Notify patron" check box should appear as shown in the wireframe RequestDetailWithModal.png
2. Scenario
   • Given a "Notify patron" check box
   • When checked
   • Then a "notify = yes" flag should be set in the request that can be used by other processes (e.g. like batch notifications as an indication that the cancellation needs to be communicated to the patron)
3. Scenario
   • Given a "Notify patron" check box
   • When un-checked
   • Then a "notify = no" flag should be set in the request that can be used by other processes (e.g. like batch notifications as an indication that the cancellation does not need to be communicated to the patron)