[FIX] : fix the compilation of the std::filesystem

Author: aiekick

ImGuiFileDialog.cpp

@@ -438,6 +438,7 @@ class FileSystemStd : public IGFD::IFileSystem {
         return false;  // this is not a directory!
     }
     bool IsFileExist(const std::string& vName) override {
+        namespace fs = std::filesystem;
         return fs::is_regular_file(vName);
     }
     bool CreateDirectoryIfNotExist(const std::string& vName) override {

ImGuiFileDialog.h

@@ -1628,6 +1628,7 @@ class IGFD_API FileInfos {
 
 class IFileSystem {
 public:
+    virtual ~IFileSystem() = default;
     // say if a directory can be openened or for any reason locked
     virtual bool IsDirectoryCanBeOpened(const std::string& vName) = 0;
     // say if a directory exist