Get should return purchase receitpt / content payment fields consistently

[tzarebczan]

If you call get outside of the SDK with the original purchase, or if the file is deleted, get no longer returns purchase_receipt / content_payment fields

[kauffj]

Related: my wallet should be the only source of purchase history. Database state should not be used to check whether something has been purchased (unless it's being kept in sync with wallet state).

[tzarebczan]

It's not. But this reminds me that we do need to have a way of marking something as hidden/deleted - this is a common request. Will file that separately.