Add callbacks to dashboard portlet rendering

In some cases, we might want to change portlet attributes
before rendering it, skip it, or even update HasResults
attribute after the portlet has been rendered.

share/html/Dashboards/Elements/ShowPortlet/dashboard

@@ -77,6 +77,13 @@ Abort("Possible recursive dashboard detected.") if $Depth > 8;
 <%perl>
 local $session{CurrentUser} = $session{ContextUser};
 for my $portlet (@panes) {
+
+    my $skip_portlet = 0;
+    $m->callback(CallbackName => 'BeforeComponent', Dashboard => $Dashboard,
+        HasResults => $HasResults, Portlet => $portlet, ARGSRef => \%ARGS,
+        SkipPortlet => \$skip_portlet);
+    next if $skip_portlet;
+
     $m->comp($portlet->{portlet_type},
         Portlet    => $portlet,
         Rows       => $Rows,
@@ -86,6 +93,10 @@ for my $portlet (@panes) {
         Depth      => $Depth + 1,
         HasResults => $HasResults
     );
+
+    $m->callback(CallbackName => 'AfterComponent', Dashboard => $Dashboard,
+        HasResults => $HasResults, Portlet => $portlet, ARGSRef => \%ARGS);
+
 }
 </%perl>