Debugger: Delay restoration until Devices are restored

Change-Id: Ib3f63e84959518cd629cb98e3e348aea50979927
Reviewed-by: hjk <hjk@qt.io>

src/plugins/debugger/debuggeritemmanager.h

@@ -22,6 +22,8 @@ public:
     DebuggerItemManager();
     ~DebuggerItemManager();
 
+    void extensionsInitialized();
+
     static const QList<DebuggerItem> debuggers();
 
     static QVariant registerDebugger(const DebuggerItem &item);