Rename namespace Core::Utils into Utils

Also move Designer::Internal::FormWindowEditor ->
Designer::FormWindowEditor.

src/libs/utils/submitfieldwidget.cpp

@@ -22,8 +22,7 @@ static void inline setComboBlocked(QComboBox *cb, int index)
     cb->blockSignals(blocked);
 }
 
-namespace Core {
-    namespace Utils {
+namespace Utils {
 
 // Field/Row entry
 struct FieldEntry {
@@ -341,4 +340,3 @@ void SubmitFieldWidget::slotBrowseButtonClicked()
 }
 
 }
-}