[doc] Use \file in headers. Replace @ with \.

This unifies the doxygen headers. If the (doxygen) header is not
starting with \file, the following documentation is attributed to a
different entity resulting is multiple copyright blocks and the like in
the doxygen's html files.

Applications/ApplicationsLib/LinearSolverLibrarySetup.h

 /**
+ * \file
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)
  *            Distributed under a Modified BSD License.

Applications/ApplicationsLib/ProjectData.cpp

 /**
+ * \file
  * \author Karsten Rink
  * \date   2010-08-25
  * \brief  Implementation of the project data class.

Applications/ApplicationsLib/ProjectData.h

 /**
+ * \file
  * \author Karsten Rink
  * \date   2010-08-25
  *

Applications/ApplicationsLib/Simulation.cpp

 /**
- * \brief  Implementation of class Simulation
  * \file
+ * \brief  Implementation of class Simulation
  *
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)

Applications/ApplicationsLib/Simulation.h

 /**
- * \brief  Declaration of class Simulation
  * \file
+ * \brief  Declaration of class Simulation
  *
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)

Applications/CLI/CommandLineArgumentParser.cpp

 /**
- * \brief  Implementation of CommandLineArgumentParser.
  * \file
+ * \brief  Implementation of CommandLineArgumentParser.
  *
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)

Applications/CLI/CommandLineArgumentParser.h

 /**
- * \brief  Declaration of CommandLineArgumentParser.
  * \file
+ * \brief  Declaration of CommandLineArgumentParser.
  *
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)

Applications/CLI/ogs.cpp

 /**
+ * \file
  * \date   2014-08-04
  * \brief  Implementation of OpenGeoSys simulation application
  *

Applications/CLI/ogs_embedded_python.cpp

 /**
+ * \file
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)
  *            Distributed under a Modified BSD License.

Applications/CLI/ogs_embedded_python.h

 /**
+ * \file
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)
  *            Distributed under a Modified BSD License.

Applications/DataExplorer/DataView/MeshMapping2DDialog.cpp

 /**
+ * \file
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)
  *            Distributed under a Modified BSD License.

Applications/DataExplorer/DataView/MeshMapping2DDialog.h

 /**
+ * \file
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)
  *            Distributed under a Modified BSD License.

Applications/DataExplorer/VtkVis/NetCdfConfigureDialog.cpp

 /**
+ * \file
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (https://www.opengeosys.org)
  *            Distributed under a Modified BSD License.

Applications/DataExplorer/VtkVis/NetCdfConfigureDialog.h

 /**
+ * \file
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (https://www.opengeosys.org)
  *            Distributed under a Modified BSD License.

Applications/DataExplorer/VtkVis/VtkCompositeImageToPointCloudFilter.cpp

 /**
+ * \file
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)
  *            Distributed under a Modified BSD License.

Applications/DataExplorer/VtkVis/VtkCompositeImageToPointCloudFilter.h

 /**
+ * \file
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)
  *            Distributed under a Modified BSD License.

Applications/DataExplorer/VtkVis/VtkCompositeImageToSurfacePointsFilter.cpp

 /**
+ * \file
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)
  *            Distributed under a Modified BSD License.

Applications/DataExplorer/VtkVis/VtkCompositeImageToSurfacePointsFilter.h

 /**
+ * \file
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)
  *            Distributed under a Modified BSD License.

Applications/DataExplorer/VtkVis/VtkConsoleOutputWindow.cpp

 /**
+ * \file
  *
  * \copyright
  * Copyright (c) 2012-2023, OpenGeoSys Community (http://www.opengeosys.org)

Applications/DataExplorer/VtkVis/VtkConsoleOutputWindow.h

 /**
+ * \file
  * \brief  VtkWin32ConsoleOutputWindow is used to suppress message boxes on
  * Windows.
  *