Be able to split studio application in several modules

When contributing new platforms (CMF etc) to studio one should be able to use a different plugin to avoid putting the code in studio-ui.
Thus, a metadata plugin studio-app will be created to create the structure of the final application (inherits all modules which compose studio).
The main plugin studio-ui will be renamed to studio-core.
In the dev mode you should launch studio-app (you can still launch studio-ui if you want to work only on the main studio plugin)