Qt6 Migration: Complete migration with DDS/RTI support and build validation

Major Changes:
- Merged latest Qt5 devel content from dlbo (292 files changed, 7 new dirs)
- Consolidated forward-declarations and include folders
- Removed unneeded modules per Niklas' repo check list

Build System Fixes:
- Fixed CMake VERSION_GREATER syntax in ParticipantManagement/CMakeLists.txt
- Added VLC packages (libvlc-dev, vlc-plugin-base) to docker_build.sh
- Added PostgreSQL dev packages (libpq-dev, postgresql-server-dev-all) to Dockerfile
- Fixed locale warnings (ANSI_X3.4-1968 → C.UTF-8)
- Fixed ArcGIS SDK path warnings when BUILD_ARCGIS=OFF

Code Generation Fixes:
- Fixed IDL enum collisions (PortType→CorePortType/DdsutPortType, PdmEventType)
- Fixed Grantlee template svc_translation.cpp.grantlee:
  - Changed {{ idl_enum.name }}_def:: to {{ idl_enum.name }}::
  - Fixed .underlying() calls for C++11 scoped enums (enum class)
- Removed generated files from repo (moc_*, *_dtc.h, *_ftc.h)

Validation:
- BUILD_RTI=ON: SUCCESS
- BUILD_RTI=OFF: SUCCESS
- C++17 standard maintained for RTI 7.7 compatibility
- Ubuntu 26.04 Docker environment verified

Remaining Warnings (expected):
- BgViewer, KDChart, KDReports, Poppler-Qt6 not found (optional features)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

qt5-before/dlbo/Lts/Tools/Splash/main.cpp

@@ -0,0 +1,67 @@
+/**
+  * @RDE_HEADER@
+  * Splash Application
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  *
+  * Created by Mike Wille, NLE, 2019-06-21
+  */
+
+#include "Splash.h"
+
+#include <LtsPluginManager/lts_plugin_manager.h>
+#include <LtsPluginManager/lts_plugin_loader.h>
+#include <nglapplication/nglapplication.h>
+#include <nglapplication/nglloggerhandler.h>
+#include <NGLLogger/INGLLogger.h>
+
+#include <QApplication>
+#include <QDebug>
+
+
+int main(int argc, char **argv)
+{
+  NGLApplication app(argc, argv);
+  app.createLogger("Splash");
+  //QNetworkProxy::setApplicationProxy(QNetworkProxy());
+
+  QStringList args(QApplication::arguments());
+  QStringList langs({ QStringLiteral("en_GB"), QStringLiteral("en_US"), QStringLiteral("de_DE") });
+
+  if (args.count() < 3)
+  {
+    qWarning() << "usage:" << QApplication::arguments().at(0) << "<branding> <language "<<langs<<">]";
+    return -1;
+  }
+
+  const QString &lang = args.at(2);
+  if (!args.contains(lang))
+  {
+    qWarning() << "unknown language iso code - available iso codes:" << langs;
+    return -1;
+  }
+
+
+  // Load Plugins
+  LtsPluginManager::LtsPluginLoader *pluginLoader = LtsPluginManager::LtsPluginLoader::getInstance();
+
+  QString projectPluginName = QApplication::arguments().at(1);
+
+  if (projectPluginName.isEmpty())
+  {
+    qWarning() << "No Project Plugin Iid specified - abort.";
+    return -1;
+  }
+
+  // load project plugin
+  if (!pluginLoader->loadPlugins(LtsPluginManager::PluginType::PROJECT, nullptr, {projectPluginName}))
+  {
+    qWarning() << "Error loading Project Plugin - abort.";
+    return -1;
+  }
+
+  QScopedPointer<Splash> s(new Splash(lang));
+
+  return app.exec();
+}