Add support for package samples

[Bian-Sh]

How about add this feature?

References:

为 Unity Package Manager 管理的插件配置示例 - 简书
https://www.jianshu.com/p/f846652b97c4

[jeffcampbellmakesgames]

In terms of priority, this is definitely lower for me to implement at this time. If you can do some research and provide more detailed information on what's needed to accomplish this or implement it yourself and put up a PR I would definitely consider it.