Enable LiveSync during bundling

[Mitko-Kerezov]

Enable LiveSync during bundling

Some bundler plugins (for example nativescript-dev-webpack) have the ability to be launched with a watcher and perform incremental bundling while watching for file changes. CLI should provide a way for such plugins to plug into the LiveSync pipeline.

Ultimately tns run <platform> --bundle should watch for file changes and LiveSync them correctly.

[Natalia-Hristova]

This is enabled in nativescript 4.0.0
Checked in Angular (changed .html, .ts, .css) and non-Angular (changed .js, .xml, .css) apps, for iOS and Android, for both - emulator/simulator and device`.