Add support to redirect to noop.json

There ar ea couple of AdGuard filters supporting this local
resource.

Reference:
https://github.com/AdguardTeam/Scriptlets/blob/master/wiki/about-redirects.md#noopjson

Author: gorhill

src/js/redirect-engine.js

@@ -38,6 +38,7 @@ const extToMimeMap = new Map([
     [  'gif', 'image/gif' ],
     [ 'html', 'text/html' ],
     [   'js', 'text/javascript' ],
+    [ 'json', 'application/json' ],
     [  'mp3', 'audio/mp3' ],
     [  'mp4', 'video/mp4' ],
     [  'png', 'image/png' ],

src/js/redirect-resources.js

@@ -162,6 +162,10 @@ export default new Map([
         alias: [ 'noopjs', 'abp-resource:blank-js' ],
         data: 'text',
     } ],
+    [ 'noop.json', {
+        alias: [ 'noopjson' ],
+        data: 'text',
+    } ],
     [ 'noop.txt', {
         alias: 'nooptext',
         data: 'text',

src/web_accessible_resources/noop.json

@@ -0,0 +1 @@
+{}