Proposal: In-memory compilation

[shiv19]

https://github.com/NativeScript/nativescript-dev-webpack/issues/1027 Quote from @DimitarTachev

Maybe we can get the Webpack compilation faster if we stop writing the output files to the platforms directory and start syncing them directly to the device (something similar to the webpack-dev-middleware but in the NativeScript CLI, not an express server).