Typescriptify the main process code (1/N)

Summary:
As a first step I've configured bundling for the main process code using Metro. For now I haven't converted anything to ts, just made that possible.

The bundle is just produced into the "static" directory. To avoid too many changes I kept the "static" folder as it is, but probably non-static code should be moved from there.

Also installed modules from "node_modules" for the main process are not bundled to avoid potential issues with node native modules.

Reviewed By: mweststrate

Differential Revision: D19960982

fbshipit-source-id: efbd426254e2b37c913c5f5f75f042c50ccee2f3

scripts/start-dev-server.js

@@ -17,6 +17,7 @@ const Convert = require('ansi-to-html');
 const chalk = require('chalk');
 const http = require('http');
 const path = require('path');
+const {compileMain} = require('./build-utils');
 const Metro = require('../static/node_modules/metro');
 const MetroResolver = require('../static/node_modules/metro-resolver');
 const fs = require('fs');
@@ -245,6 +246,7 @@ function outputScreen(socket) {
   const socket = await addWebsocket(server);
   await startMetroServer(app);
   outputScreen(socket);
+  await compileMain();
   shutdownElectron = launchElectron({
     devServerURL: `http://localhost:${port}`,
     bundleURL: `http://localhost:${port}/src/init.bundle`,