Make flipper-server stand-alone servable

Summary:
This diff makes flipper-server stand-alone servable as a single package.

It basically works as follows:

- (default) plugins are build as usually into static folder
- static folder is copied into flipper-server/static (as far as relevant)
- `flipper-server/src/index.tsx` is bundled into `flipper-server/dist/index.js`
- `flipper-ui-browser/src/index.tsx` is bundled into `flipper-server/static/bundle.js`

If flipper-server is started without the `--bundler` config, the `bundle.js` will be served statically, rather than starting up the Metro bundler with all the typical transforms (in a distributed version of the package those all wouldn't resolve)

Things to be done in next diffs:

* make sure plugins actually load in the non bundled setup
* make sure flipper-server gets published properly
* make sure build is created as part of CI

At the end of this stack, running `npx flipper-server` on any machine should basically be a viable approach to get flipper up and running locally :)

Reviewed By: nikoant

Differential Revision: D33171107

fbshipit-source-id: 4af8ac2699467a0b55283fe084640482700744c2

desktop/flipper-server/package.json

@@ -5,6 +5,7 @@
   "description": "Standalone nodeJS based Flipper server",
   "repository": "facebook/flipper",
   "main": "server.js",
+  "bin": "server.js",
   "flipperBundlerEntry": "src",
   "license": "MIT",
   "bugs": "https://github.com/facebook/flipper/issues",
@@ -22,7 +23,9 @@
     "flipper-common": "0.0.0",
     "flipper-pkg-lib": "0.0.0",
     "flipper-server-core": "0.0.0",
-    "metro": "^0.66.2"
+    "metro": "^0.66.2",
+    "open": "^8.3.0",
+    "yargs": "^17.0.1"
   },
   "peerDependencies": {},
   "scripts": {
@@ -31,7 +34,8 @@
     "prepack": "yarn reset && yarn build"
   },
   "files": [
-    "dist/**/*"
+    "dist/**/*",
+    "static/**/*"
   ],
   "homepage": "https://github.com/facebook/flipper",
   "keywords": [