feat(frontend): Custom widget embed

If widget variable exists in /etc/rvd_front.conf the widget is embeded
  ,widget => '/js/custom/insert_here_widget.js'

The widged script must be in public/js/custom/insert_here_widget.js

Issue #1419

etc/rvd_front.conf.example

@@ -37,4 +37,7 @@
       ,file => '/var/log/ravada/rvd_front.log'
       ,level => 'debug'
   }
+# Insert widget in /js/custom/insert_here_widget.js
+# this widget embed js in templates/bootstrap/scripts.html.ep
+  ,widget => ''
 };

script/rvd_front

@@ -66,7 +66,7 @@ my $CONFIG_FRONT = plugin Config => { default => {
                                               ,monitoring => 0
                                               ,fallback => 0
                                               ,guide_custom => ''
-                                              ,widget_footer => ''
+                                              ,widget => ''
                                               ,admin => {
                                                     hide_clones => 15
                                                     ,autostart => 0
@@ -156,7 +156,7 @@ hook before_routes => sub {
             ,check_netdata => 0
             ,guide => $CONFIG_FRONT->{guide}
             ,host => $host
-            ,widget_footer => $CONFIG_FRONT->{widget_footer}
+            ,widget => $CONFIG_FRONT->{widget}
             );
 
     $USER = _logged_in($c);

templates/bootstrap/scripts.html.ep

@@ -62,4 +62,7 @@
         document.getElementById("spinn"+iD).style.display="none";
     }
 </script>
-<script src="<%= $widget_footer %>"></script>
+
+% if ( $widget ) {
+<script src="<%= $widget %>"></script>
+% }