Configurable conventions

This is a feature request / question.

I'm trying to implement the parser for an unity application. Sadly unity uses different conventions for command line arguments: https://docs.unity3d.com/Manual/CommandLineArguments.html

Is there any way I can configure the parser to use single dashes for the full name (and single dashes for spaces)?

Currently it's not possible for me to use both concurrently:

```ps
& '.\My UnityApp.exe' --configpath="config.json" -logFile log.txt -screen-fullscreen
1 -screen-height 1200 -screen-width 1920
```

Breaks because `RepeatedOptionError` at `configpath`. I understand why this happens but it's blocking me currently.

Does this require a change on the source code of the parser or am I missing something?

首先，重现 issue 中显示的 Unity 命令，并追踪解析器在何处为 configpath 引发 RepeatedOptionError。然后检查解析器的配置入口，以确定是否可以同时支持带单个连字符的完整名称和现有约定。完成标准是命令解析时不再出现该错误，且现有参数约定仍保持兼容。

由索引模型根据 Issue 内容生成。