Add new scriptlet to allow blocking Amazon's apstag.js

Related issues:
- NanoMeow/QuickReports#3717
- https://www.reddit.com/r/uBlockOrigin/comments/ghjqph/

The specific issue on the mentioned site is that the
site's code expect `window.apstag.fetchBids` to call
client-supplied function. The new scriptlet defuse this
by calling the client code with an empty array.

src/js/redirect-engine.js

@@ -59,6 +59,8 @@ const redirectableResources = new Map([
     [ 'amazon_ads.js', {
         alias: 'amazon-adsystem.com/aax2/amzn_ads.js',
     } ],
+    [ 'amazon_apstag.js', {
+    } ],
     [ 'ampproject_v0.js', {
         alias: 'ampproject.org/v0.js',
     } ],

src/web_accessible_resources/amazon_apstag.js

@@ -0,0 +1,42 @@
+/*******************************************************************************
+
+    uBlock Origin - a browser extension to block requests.
+    Copyright (C) 2019-present Raymond Hill
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see {http://www.gnu.org/licenses/}.
+
+    Home: https://github.com/gorhill/uBlock
+*/
+
+// https://www.reddit.com/r/uBlockOrigin/comments/ghjqph/
+// https://github.com/NanoMeow/QuickReports/issues/3717
+
+(function() {
+    'use strict';
+    const w = window;
+    const noopfn = function() {
+        ; // jshint ignore:line
+    }.bind();
+    const apstag = {
+        fetchBids: function(a, b) {
+            if ( b instanceof Function ) {
+                b([]);
+            }
+        },
+        init: noopfn,
+        setDisplayBids: noopfn,
+        targetingKeys: noopfn,
+    };
+    w.apstag = apstag;
+})();