Automate project generation for webui itests in Studio

At the moment, we rely on html files extracted manually from the Studio project studio-webui-itest to generate the test jars for itests. 

We should use DesignerServices to generate the html from the inner model used by Designer. 

As a first step, we should create a script to automatically extract the model from the project files and use that for the scaffold engine during the nuxeo-studio-tests  to generate the final html to be included in the jars and used in itests.