Counts of one customer's mail held by the PHI screen

#1122. For a PHI-bounded customer, how many Gmail messages the PHI screen holds now, by held reason and by the UTC week (Monday) each was received over the last eight weeks, and how many a later sync released. Counts only: held rows store no sender, subject or file name. Any other customer answers bounded: false. Requires assignment to the customer (403 otherwise). A failed read of the flag or the rows is 503, never an empty answer.