[LiveSync] allow for custom files (extensions) to be handled by liveSync

[farfromrefug]

In my app i need to allow fast live sync for files ".mss"
When those files are changed (in assets), only a reload of the map style is needed.
I already handle that through global.__onLiveSync

But now it does not work anymore. It comes from that line:

nativescript-cli/lib/services/webpack/webpack-compiler-service.ts

Line 59 in 5069f29

hasOnlyHotUpdateFiles: files.every(f => f.indexOf("hot-update") > -1),

I was working a few releases before. If i

Here only files with 'hot-update' will allow live sync. How can i make it work?
Actually how does it work today for images live sync. I can see that it is supposed to be handled seeing fastLivesyncFileExtensions:

nativescript-cli/lib/services/android-project-service.ts

Line 85 in 9320a1d

fastLivesyncFileExtensions: [".jpg", ".gif", ".png", ".bmp", ".webp"] // http://developer.android.com/guide/appendix/media-formats.html