Split package "flipper-pkg" into two: lib and cli

Summary: "flipper-pkg" added ~2MB to Flipper disttributive size, because of heavy dependencies which are only required for CLI functionality. See size warning in diff D21068373 in this stack where I added pkg as dependency to flipper. Here I'm splitting it into library and CLI packages, so Flipper app will only reference the library.

Reviewed By: passy

Differential Revision: D21087336

fbshipit-source-id: d9d62f1e75a835d1c0fa78ff1addb0d9a761a9c7

desktop/pkg-lib/src/index.ts

@@ -0,0 +1,11 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+export {default as runBuild} from './runBuild';
+export {default as getWatchFolders} from './getWatchFolders';