QmlDesigner: Avoid duplicate module names

We get every qmldir file twice and some files report QtQuick
multiple times.

This needs to be revisited.

Change-Id: I2271f71ee7da2c182fed468fa3ef8aca63785bb4
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmldesigner/designercore/projectstorage/modulescanner.cpp

@@ -9,6 +9,7 @@
 
 #include <QDirIterator>
 #include <QFile>
+#include <QHash>
 
 namespace QmlDesigner {
 
@@ -50,6 +51,8 @@ void ModuleScanner::scan([[maybe_unused]] std::string_view modulePath)
 #ifdef QDS_HAS_QMLPRIVATE
     QDirIterator dirIterator{QString::fromUtf8(modulePath), QDir::Dirs, QDirIterator::Subdirectories};
 
+    QMap<QString, bool> moduleNames;
+
     while (dirIterator.hasNext()) {
         auto directoryPath = dirIterator.next();
         QString qmldirPath = directoryPath + "/qmldir";
@@ -69,6 +72,10 @@ void ModuleScanner::scan([[maybe_unused]] std::string_view modulePath)
             if (moduleName.isEmpty() || m_skip(moduleName))
                 continue;
 
+            if (moduleNames.contains(moduleName))
+                continue;
+
+            moduleNames.insert(moduleName, true);
             m_modules.push_back(
                 Import::createLibraryImport(moduleName, createVersion(parser.components())));
         }