Method IsFileExist

ImGuiFileDialog.cpp:486–489

        return false;  // this is not a directory!
    }
    bool IsFileExist(const std::string& vName) override {
        namespace fs = std::filesystem;
        return fs::is_regular_file(stringToPath(vName));
    }
    bool CreateDirectoryIfNotExist(const std::string& vName) override {
        if (vName.empty()) return false;
        if (IsDirectoryExist(vName)) return true;