chore: Change response of shares.info response for unshared document (#1666)

* Update server/api/share.js to send 204 status for unshared documents.

* Update shares.info endpoint to expect 204 in a few test.

* Update SharesStore and ApiClient to handle 204 status code

app/utils/ApiClient.js

@@ -110,6 +110,8 @@ class ApiClient {
 
       download(blob, trim(fileName, '"'));
       return;
+    } else if (success && response.status === 204) {
+      return;
     } else if (success) {
       return response.json();
     }