Make some headers self-contained

This fixes the build in certain configurations, e.g. MSVC + qbs + Qt 6.

Change-Id: Ia72dfd6dcfe1d1ecc08c40a3af6e60a935dc355f
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/utils/namevaluesdialog.h

@@ -26,6 +26,7 @@
 #pragma once
 
 #include "environmentfwd.h"
+#include "namevalueitem.h"
 #include "optional.h"
 #include "utils_global.h"
 

src/plugins/cppcheck/cppcheckrunner.h

@@ -25,14 +25,12 @@
 
 #pragma once
 
+#include <utils/filepath.h>
+
 #include <QHash>
 #include <QTimer>
 
-namespace Utils {
-class QtcProcess;
-class FilePath;
-using FilePaths = QList<FilePath>;
-}
+namespace Utils { class QtcProcess; }
 
 namespace Cppcheck {
 namespace Internal {