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/build-release.js

@@ -15,6 +15,7 @@ const cp = require('promisify-child-process');
 const {
   buildFolder,
   compile,
+  compileMain,
   die,
   compileDefaultPlugins,
   getVersionNumber,
@@ -168,6 +169,7 @@ function downloadIcons(buildFolder) {
   const dir = await buildFolder();
   // eslint-disable-next-line no-console
   console.log('Created build directory', dir);
+  await compileMain();
   copyStaticFolder(dir);
   await downloadIcons(dir);
   await compileDefaultPlugins(path.join(dir, 'defaultPlugins'));