Experimental Features/Tech Preview framework

Sometimes we are developing features that won't be present on the product in a short term but might be interesting for users/clients to preview them to have a view of "where we are going". Another option is to also be able to have a mechanism to handle 'tech preview' features.'

The idea is creating a framework on appformer to let the users expose this on going features so they can preview them and see how they look like.

By default this framework will be disabled in product but enabled on our showcases. It can be enabled setting the system property "appformer.experimental.features" to true.

Appformer Componentes like Screens, Editors, Perspectives, LayoutComponentes and also Menu should be able to define this in a clear way (@ExperimentalFeatures annotation or expeirmental() in menus fluent API)