Yarn workspaces

Summary:
1) moved "sonar/desktop/src" to "sonar/desktop/app/src", so "app" is now a separate package containing the core Flipper app code
2) Configured yarn workspaces with the root in "sonar/desktop": app, static, pkg, doctor, headless-tests. Plugins are not included for now, I plan to do this later.

Reviewed By: jknoxville

Differential Revision: D20535782

fbshipit-source-id: 600b2301960f37c7d72166e0d04eba462bec9fc1

desktop/scripts/build-headless.ts

@@ -14,7 +14,7 @@ import yazl from 'yazl';
 const {exec: createBinary} = require('pkg');
 import {
   buildFolder,
-  compile,
+  compileHeadless,
   compileDefaultPlugins,
   getVersionNumber,
   genMercurialRevision,
@@ -98,7 +98,7 @@ async function createZip(buildDir: string, distDir: string, targets: string[]) {
   const distDir = path.join(__dirname, '..', '..', 'dist');
   // eslint-disable-next-line no-console
   console.log('Created build directory', buildDir);
-  await compile(buildDir, path.join(__dirname, '..', 'headless', 'index.tsx'));
+  await compileHeadless(buildDir);
   const versionNumber = getVersionNumber();
   const buildRevision = await genMercurialRevision();
   await preludeBundle(buildDir, versionNumber, buildRevision);