CMakeProjectManager: Some code cosmetics

Move non-exported classed to Internal namespace, move some functions
out-of-line.

Change-Id: I3a2135104d09c0c3f799c5b8d795c93059b1ae95
Reviewed-by: Cristian Adam <cristian.adam@qt.io>

src/plugins/cmakeprojectmanager/configmodelitemdelegate.h

@@ -32,6 +32,7 @@
 #include <QStyledItemDelegate>
 
 namespace CMakeProjectManager {
+namespace Internal {
 
 class ConfigModelItemDelegate : public QStyledItemDelegate
 {
@@ -51,4 +52,5 @@ private:
     Utils::FilePath m_base;
 };
 
+} // namespace Internal
 } // namespace CMakeProjectManager