[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

Comienza por los puntos de entrada de la CLI para tns run y tns debug, centrándote en su ciclo de vida en modo watch y en el manejo de la entrada del terminal. Define cómo deben interactuar la observación suspendida, la observación reanudada y el despliegue manual, y verifica después que los comandos solicitados s, r y d funcionen sin detener el comando en ejecución.