[Navigator] Add an empty all_panels manifest for the sidebar so it stops trying a long dead URL

navigator/app/defaults/pref/navigator-prefs.inc.js

@@ -357,7 +357,7 @@ pref("custtoolbar.personal_toolbar_folder", "");
 // Use a popup window for the customize toolbar UI
 pref("toolbar.customization.usesheet", false);
 
-pref("sidebar.customize.all_panels.url", "http://sidebar-rdf.netscape.com/%LOCALE%/sidebar-rdf/%SIDEBAR_VERSION%/all-panels.rdf");
+pref("sidebar.customize.all_panels.url", "chrome://communicator/content/sidebar/all-panels.rdf");
 pref("sidebar.customize.directory.url", "https://edmullen.net/mozilla/moz_sidebar.php");
 pref("sidebar.customize.more_panels.url", "https://edmullen.net/mozilla/moz_sidebar.php");
 pref("sidebar.num_tabs_in_view", 8);

navigator/components/sidebar/content/all-panels.rdf

@@ -0,0 +1,4 @@
+<?xml version="1.0"?>
+
+<RDF:RDF xmlns:RDF="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+         xmlns:NC="http://home.netscape.com/NC-rdf#" />

navigator/components/sidebar/jar.mn

@@ -3,6 +3,7 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 comm.jar:
+  content/communicator/sidebar/all-panels.rdf                      (content/all-panels.rdf)
   content/communicator/sidebar/customize-panel.js                  (content/customize-panel.js)
   content/communicator/sidebar/customize-panel.xul                 (content/customize-panel.xul)
   content/communicator/sidebar/customize.js                        (content/customize.js)