message: Use some more axom string utilities.
diff: @@ -800,15 +800,14 @@ std::string IOManager::getFileNameForRank(const std::string& file_pattern,
  axom::Path root_path(root_name);
  std::string root_dir = root_path.dirName();
  - if(!root_name.empty() && root_name[0] == delimiter[0])
  + if(!root_name.empty() &&
  + axom::utilities::string::startsWith(root_name, delimiter[0]))
  {
  root_dir = delimiter + root_dir;
  }
  - if(!root_dir.empty())
  - {
  - file_name = root_dir + delimiter + file_name;
  - }
  + file_name =
  + axom::utilities::string::appendPrefix(root_dir, file_name, delimiter[0]);
  return file_name;
  }
  