Utils: Make Layouting a top level namespace

The whole machinery is now almost only layoutbuilder.{h,cpp},
mostly independent of the rest of Utils. Idea is to finish the
separation to make it stand-alone usable also outside creator.

Change-Id: I958aa667d17ae26b21209f22412309c5307a579c
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/cmakeprojectmanager/cmakeformatteroptionspage.cpp

@@ -59,7 +59,7 @@ CMakeFormatterOptionsPageWidget::CMakeFormatterOptionsPageWidget()
     m_command->setPromptDialogTitle(Tr::tr("%1 Command").arg(Tr::tr("Formatter")));
     m_command->setFilePath(settings->command());
 
-    using namespace Utils::Layouting;
+    using namespace Layouting;
 
     Column {
         Group {

src/plugins/cmakeprojectmanager/cmakekitinformation.cpp

@@ -49,7 +49,7 @@
 
 using namespace ProjectExplorer;
 using namespace Utils;
-using namespace Utils::Layouting;
+using namespace Layouting;
 
 namespace CMakeProjectManager {