Nested dependencies of geppetto inside geppetto-client makes development quite hard

As recently experienced by @aranega, currently the geppetto-client has as dependencies the [geppetto core and geppetto ui](https://github.com/MetaCell/geppetto-meta/blob/113a847b8eca6ccd788033b613e1f327a1a25e37/geppetto.js/geppetto-client/package.json#L30), that makes the development process, if you need to change anything imported by the geppetto client (e.g. flexlayout), impossible development wise since yalc nesting of dependencies is not supported.

To me these 3 packages should not really depend on each other, otherwise we have decoupled them physically in different folders but not logically.