Converting from boost to std::filesystem

[Nelson-numerical-software]

Nelson uses boost because C++17 was not available
Now we can switch boost::filesystem to std::filesystem

222 references to boost::filesystem
some will be not removed for example with it is used with boost ipc features

[Nelson-numerical-software]

gcc bug :(
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95048

[Nelson-numerical-software]

ugly workaround on gcc use character_encoding functions

 #include <filesystem>
 #include "IsDirectory.hpp"
 #include "Error.hpp"
+#include "characters_encoding.hpp"
 //=============================================================================
 namespace Nelson {
 //=============================================================================
 bool
 IsDirectory(const std::wstring& str)
 {
-    std::filesystem::path data_dir(str);
+    std::string s = wstring_to_utf8(str);
+    std::filesystem::path data_dir(s);
     bool bRes = false;
     try {
-        bRes = std::filesystem::is_directory(data_dir);
+        
+      bRes = std::filesystem::is_directory(data_dir);
     } catch (const std::filesystem::filesystem_error& e) {
         if (e.code() == std::errc::permission_denied) {
             Error(_W("Permission denied."));
diff --git a/modules/files_folders_functions/src/cpp/MakeDirectory.cpp b/modules/files_folders_functions/src/cpp/MakeDirectory.cpp
index 2c5d5be84..63ec78abd 100644
--- a/modules/files_folders_functions/src/cpp/MakeDirectory.cpp
+++ b/modules/files_folders_functions/src/cpp/MakeDirectory.cpp
@@ -33,7 +33,8 @@ MakeDirectory(const std::wstring& newDir, std::wstring& message)
         message = _W("Directory already exists.");
     } else {
         try {
-            bOK = std::filesystem::create_directories(newDir);
+            std::string s = wstring_to_utf8(newDir);
+            bOK = std::filesystem::create_directories(s);
         } catch (const std::filesystem::filesystem_error& e) {
             std::error_code error_code = e.code();

major rework for a ugly bug of gcc ...