Remove 'path' from plugins

Summary:
1. Add `path` replacement
1. Remove Node's path for all plugins but MobileBuildsPluginContainer (it is probably going to be moved to the server)

Reviewed By: mweststrate

Differential Revision: D32766327

fbshipit-source-id: e636f273842506e752b97cf1b28ce7ac51ce9a12

desktop/flipper-plugin/src/__tests__/api.node.tsx

@@ -56,6 +56,7 @@ test('Correct top level API exposed', () => {
       "createState",
       "createTablePlugin",
       "getFlipperLib",
+      "path",
       "produce",
       "renderReactRoot",
       "sleep",