addCommand method
Adds a new command with the given id
to this command set.
Implementation
CommandParser addCommand(T id,
{String? description, UsageGroup? usageGroup}) {
var added = _base.addCommand(
id: id, description: description, usageGroup: usageGroup);
var parser = CommandParser._(parent, added.command, added.subBase);
parent._commandParsers[_base.commandSet.printer(id)] = parser;
return parser;
}