Add CGAL/version_checker.h (#7528)

## Summary of Changes

Following discussion #7525 I added the header `version_enforcer.h`

In the general case, it has nothing to check. If the user includes his
own fork of `version_enforcer.h` with a given number of CGAL version,
then the check happens.

## Release Management

* Affected package(s): Installation

Installation/include/CGAL/config.h

@@ -112,6 +112,7 @@
 #include <boost/version.hpp>
 
 #include <CGAL/version.h>
+#include <CGAL/version_checker.h>
 
 //----------------------------------------------------------------------//
 //  platform specific workaround flags (CGAL_CFG_...)

Installation/include/CGAL/version_checker.h

@@ -0,0 +1,53 @@
+// Copyright (c) 2023 GeometryFactory.
+// All rights reserved.
+//
+// This file is part of CGAL (www.cgal.org)
+//
+// $URL$
+// $Id$
+// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
+//
+// Author(s)     : -
+
+#ifndef CGAL_VERSION_CHECKER_H
+#define CGAL_VERSION_CHECKER_H
+
+#include <CGAL/version_macros.h>
+
+// All files including this header are meant to work with a given version of CGAL
+// When using forked headers, set the following macro to the version of CGAL
+// you want to use.
+
+//// Set the 3 following macros to the version of CGAL you want to use
+//#define CGAL_COMPATIBLE_VERSION_MAJOR 6
+//#define CGAL_COMPATIBLE_VERSION_MINOR 0
+//#define CGAL_COMPATIBLE_VERSION_PATCH 0
+
+// Set the following macros to 1 to get a warning/an error
+// when using a possibly incompatible version of CGAL
+#define CGAL_VERSION_CHECKER_ERROR 0
+#define CGAL_VERSION_CHECKER_WARNING 0
+
+#define CGAL_COMPATIBLE_VERSION_STR CGAL_STR(CGAL_COMPATIBLE_VERSION_MAJOR) "." \
+                                    CGAL_STR(CGAL_COMPATIBLE_VERSION_MINOR) "." \
+                                    CGAL_STR(CGAL_COMPATIBLE_VERSION_PATCH)
+
+
+// Check that the version of CGAL used is the one expected
+#if  CGAL_COMPATIBLE_VERSION_MAJOR != CGAL_VERSION_MAJOR \
+  || CGAL_COMPATIBLE_VERSION_MINOR != CGAL_VERSION_MINOR \
+  || CGAL_COMPATIBLE_VERSION_PATCH != CGAL_VERSION_PATCH
+
+    #if CGAL_VERSION_CHECKER_WARNING || CGAL_VERSION_CHECKER_ERROR
+      #pragma message("These headers are meant to be used with CGAL " CGAL_COMPATIBLE_VERSION_STR " only."\
+                       " You are using CGAL version: " CGAL_STR(CGAL_VERSION) ".")
+
+      #ifdef CGAL_VERSION_CHECKER_ERROR
+        #error "Incompatible version of CGAL"
+      #endif
+
+    #endif
+
+#endif
+
+#endif // CGAL_VERSION_CHECKER_H