PM; Add ticks around metis call input filename.

CL: "It would be better to use boost::process"
https://www.boost.org/doc/libs/1_67_0/doc/html/boost_process/tutorial.html#boost_process.tutorial.starting_a_process

Applications/Utils/ModelPreparation/PartitionMesh/PartitionMesh.cpp

@@ -136,8 +136,8 @@ int main(int argc, char* argv[])
         INFO("Path to mpmetis is: \n\t%s", exe_path.c_str());
 
         const std::string mpmetis_com =
-            exe_path + "/mpmetis " + " -gtype=nodal " +
-            input_file_name_wo_extension + ".mesh " +
+            BaseLib::joinPaths(exe_path, "mpmetis") + " -gtype=nodal " + "'" +
+            input_file_name_wo_extension + ".mesh" + "' " +
             std::to_string(nparts.getValue());
 
         const int status = system(mpmetis_com.c_str());