scanservjs: Add config overrides for PIXMA G7020

The Canon PIXMA G7020 reports the supported dimensions of the flatbed,
but its automatic document feeder supports larger paper sizes.
Fortunately, *scanserv-js* provides a (somewhat kludgey) mechanism to
override the reported settings with more appropriate values.

scanservjs/config.local.js

@@ -73,5 +73,16 @@ module.exports = {
     if (fileInfo.name.endsWith('.pdf')) {
       await paperless_send(fileInfo.fullname);
     }
+  },
+
+  afterDevices(devices) {
+    devices
+      .filter(d => d.id == 'escl:https://172.30.0.234:443')
+      .forEach(device => {
+        device.name = 'Canon PIXMA G7020';
+        device.features['-x'].limits = [0, 216];
+        device.features['-y'].limits = [0, 432];
+        device.features['-y'].default = 279.4;
+      });
   }
 }