add "logfile" option to log diagnostics to file using boost (#13931)

add some logging options

Co-authored-by: SoftFever <softfeverever@gmail.com>

src/libslic3r/utils.cpp

@@ -129,6 +129,11 @@ void set_logging_level(unsigned int level)
     );
 }
 
+void set_logging_file(const std::string &file)
+{
+	boost::log::add_file_log(file);
+}
+
 unsigned int level_string_to_boost(std::string level)
 {
     std::map<std::string, int> Control_Param;