[CLI] Manual watching the source changes

From @raffaeler on February 6, 2019 10:58

Is your feature request related to a problem? Please describe.
When tns run is started, it takes a while before deploying the application. For this reason I prefer to run in watch mode (tns run or tns debug).
Anyway, when you are doing more than a trivial change, it would be useful to manually trigger the compilation/deploy without stopping and re-running tns run or tns debug.

Describe the solution you'd like
When the terminal is in tns run or tns debug it can accept keyboard commands. It would be useful to add support for three commands while the terminal is watching:

• 's' key: suspend watching
• 'r' key: resume watching
• 'd' key: deploy while in suspended mode

Describe alternatives you've considered
Stopping and restarting tns run or tns debug is way too slow.

Copied from original issue: NativeScript/NativeScript#6865

从 tns run 和 tns debug 的 CLI 入口开始，重点关注它们的 watch 模式生命周期和终端输入处理。定义暂停 watching、恢复 watching 和手动部署之间应如何交互，然后验证所请求的 s、r 和 d 命令能够在不停止正在运行的命令的情况下工作。