expose toggleWidgetExplorer through dbus

Summary:
--shows/hides the WidgetExplorer through dbus

Test Plani: trigger widget explorer from command line

Reviewers: mart, davidedmundson, #plasma

Reviewed By: davidedmundson, #plasma

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D3754

shell/dbus/org.kde.PlasmaShell.xml

@@ -5,6 +5,8 @@
     </method>
     <method name="toggleActivityManager">
     </method>
+    <method name="toggleWidgetExplorer">
+    </method>
     <method name="setDashboardShown">
       <arg name="show" type="b" direction="in"/>
     </method>

shell/shellcorona.h

@@ -138,6 +138,7 @@ public Q_SLOTS:
     void showInteractiveKWinConsole();
     void loadKWinScriptInInteractiveConsole(const QString &script);
     void toggleActivityManager();
+    void toggleWidgetExplorer();    
     void evaluateScript(const QString &string);
     void activateLauncherMenu();
 
@@ -185,7 +186,6 @@ protected Q_SLOTS:
 private Q_SLOTS:
     void createWaitingPanels();
     void handleContainmentAdded(Plasma::Containment *c);
-    void toggleWidgetExplorer();
     void syncAppConfig();
     void checkActivities();
     void currentActivityChanged(const QString &newActivity);