Request: Support environments other than release and debug

Currently, there are two supported environments, release and debug. The default is debug and "--release" can be used to build a release version of the app. It would be useful to have other environments, so I was wondering if it would be possible to add an "--environment" flag be allowed to specify these.

For example, "tns run android --environment=test" would use the file app.component.test.ts.

从 tns run android 的 CLI 处理以及现有的 --release 和调试环境选择开始。跟踪 app.component.ts 的选择方式，然后定义 --environment=test 必须选择什么，并通过使用 app.component.test.ts 的示例命令展示完成情况。