Summary: Moved getWatchFolders script to flipper-pkg and used it from other packages. Script helps to resolve all the folders with package dependencies including symlinked folders in case if plugin is a part of yarn workspaces.
Reviewed By: mweststrate
Differential Revision: D21068373
fbshipit-source-id: 8691837fdb1aef333dab4c13d8758262838d36ee