padWidth(cmd, helper) {
    return Math.max(
      helper.longestOptionTermLength(cmd, helper),
      helper.longestGlobalOptionTermLength(cmd, helper),
      helper.longestSubcommandTermLength(cmd, helper),
      helper.longestArgumentTermLength(cmd, helper),
    );
  }
Calculate the pad width from the maximum term length.

@param {Command} cmd
@param {Help} helper
@returns {number}