[Feature] admin 增加多环境支持

[KeRan213539]

• [x] I have searched the issues of this repository and believe that this is not a duplicate.
• [x] I have checked the REAMDE of this repository and believe that this is not a duplicate.

Is your feature request related to a problem? Please describe.

目前在admin配制文件中指定环境(注册中心,namespace,gropu等设置),admin启动后只能处理这个环境中的服务

Describe the solution you'd like

增加多环境支持,能够在不重启的情况下切换环境

Describe alternatives you've considered

参考方案: https://www.yuque.com/kenliu-zhmwk/qc8gak/decib8

[KeRan213539]

@i will solve it@

[Maksim-lk]

请问这个特性支持的优先级是怎样的？完成的时间点大概是什么时候？