Split flipper-plugin package

Summary:
flipper-server-companion depends on flipper-plugin. flipper-plugin includes dependencies that run only in a browser. Splitting flipper-plugin into core and browser packages helps to avoid including browser-only dependencies into flipper-server bundle.
As a result, bundle size could be cut in half. Subsequently, RSS usage drops as there is twice as less code to process for V8.

Note: it currently breaks external flipper-data-source package. It will be restored in subsequent diffs

Reviewed By: lblasa

Differential Revision: D38658285

fbshipit-source-id: 751b11fa9f3a2d938ce166687b8310ba8b059dee

desktop/flipper-plugin/src/state/batch.tsx

@@ -8,17 +8,6 @@
  */
 
 import {unstable_batchedUpdates} from 'react-dom';
+import {_setBatchedUpdateImplementation} from 'flipper-plugin-core';
 
-export const batch = unstable_batchedUpdates;
-
-export function batched<T extends Function>(fn: T): T;
-export function batched(fn: any) {
-  return function (this: any) {
-    let res: any;
-    batch(() => {
-      // eslint-disable-next-line
-      res = fn.apply(this, arguments);
-    });
-    return res;
-  };
-}
+_setBatchedUpdateImplementation(unstable_batchedUpdates);