[Qt] Header cleanup (#6477)

Make some headers private, so we only commit with the QML API.

platform/qt/src/qquickmapboxgl.cpp

@@ -1,11 +1,11 @@
+#include "qquickmapboxgl.hpp"
+
+#include "qmapbox.hpp"
+#include "qquickmapboxglmapparameter.hpp"
 #include "qquickmapboxglrenderer.hpp"
 
 #include <mbgl/util/constants.hpp>
 
-#include <QMapbox>
-#include <QQuickMapboxGL>
-#include <QQuickMapboxGLMapParameter>
-
 #include <QDebug>
 #include <QQuickItem>
 #include <QRegularExpression>
@@ -14,7 +14,6 @@
 #include <QQmlListProperty>
 #include <QJSValue>
 
-
 namespace {
 
 static const QRegularExpression s_camelCase {"([a-z0-9])([A-Z])"};