Versioning for plugin format

Summary:
Added versioning for plugin format.

The first version is where "main" points to source code entry and plugins are bundled by Flipper in run-time on loading them.

The second version is where "main" points to the already existing bundle and Flipper just loads it without bundling. The plugins of version 2 must be bundled using "flipper-pkg" tool before publishing.

Changelog: Support new packaging format for plugins.

Reviewed By: mweststrate

Differential Revision: D21074173

fbshipit-source-id: 7b70250e48e5bd5d359c96149fb5b14e67783c4d

desktop/scripts/start-dev-server.ts

@@ -99,7 +99,7 @@ async function startMetroServer(app: Express, server: http.Server) {
     },
     resolver: {
       ...baseConfig.resolver,
-      resolverMainFields: ['flipper:source', 'module', 'main'],
+      resolverMainFields: ['flipperBundlerEntry', 'module', 'main'],
       blacklistRE: /\.native\.js$/,
       resolveRequest: (context: any, moduleName: string, platform: string) => {
         if (moduleName.startsWith('./localhost:3000')) {