Utils: More forward declarations / drop unused headers [D-G]

Round 1 - focus on headers.
For classes with initial in range [D-G].
Try to keep the same separators between different kind of headers.

Change-Id: Id42cd7b3743a816f75cecb6b576c0e37cb057473
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: hjk <hjk@qt.io>

src/plugins/qmakeprojectmanager/qmakeparsernodes.cpp

@@ -27,7 +27,6 @@
 
 #include "qmakeproject.h"
 #include "qmakeprojectmanagerconstants.h"
-#include "qmakebuildconfiguration.h"
 
 #include <android/androidconstants.h>
 #include <coreplugin/documentmanager.h>
@@ -57,6 +56,7 @@
 #include <QLoggingCategory>
 #include <QMessageBox>
 #include <QTextCodec>
+#include <QXmlStreamWriter>
 
 using namespace Core;
 using namespace ProjectExplorer;