Nativescript-cli: Add `console` command to open live REPL on running NativeScript application

[cowboyd]

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

A REPL is a developer's best friend. Sometimes you just want to play with the native JavaScript integration, or do a quick debug session without all the rigamarole of starting up a devtools session. There's nothing quite like it in terms of exploration.

Describe the solution you'd like

Add a console command that fires up a remote node REPL session to Read expressions from the local machine, Evaluate them on the device, and Print them on the local machine.

Build the app, load it onto a device, and startup a new REPL:

$ tns console ios
{N}> UIButton
[Function: UIButton]
{N}> 

or attach to an existing process:

$ tns console android --device UUID
{N}> android.widget.Button
[Function: Button]
{N}> android.widget.Button

Describe alternatives you've considered
You can use the chrome devtools coupled with the the tns debug command. It just doesn't feel as breezy.

Additional context
Node comes with repl tools out of the box that give you pretty fine grained control over where evaluation happens, how completion and history are achieved, etc....

The only thing would be to implement the remote connection to the nativescript app.

[cowboyd]

@KristianDD I saw the help wanted tag, and wanted to let you know that I would be very happy to help in the implementation of this if I could get some direction from folks familiar with NativeScript internals.

[KristianDD]