Switch to async socket lib

[theolivenbaum]

@GregorBiswanger finally had some time to prepare a PR with my changes:

Quick summary of what changed:

• Switch to a supported, asynchronous socket library (https://github.com/doghappy/socket.io-client-csharp / https://www.nuget.org/packages/SocketIOClient)
• minor changes to the data model to replace arrays with objects on the response side
• Added method to manually configure ElectronNET without using UseElectron(args) on IWebHostBuilder (something I needed)
• Added new parameter to Start command to run from build output and not from publish output
• Fix deadlock with reading properties twice, caused by the previous handler being removed by a new call to On(triggerEvent, () => { ... })
• Exit Electron process immediately if ASP.NET process exits with non-zero exit code

Would probably be good if you do a quick review of the TS changes, I had originally only changed the JS side, then noticed you were using typescript for generating it :)

Closes #431