Add Localization in Italian

[DavidLeoni]

For now we can directly put strings in English, but at some point in time it we should support localization in Italian.

In Scratch GUI translations are managed with Transifex, with build steps just for that that require an API key for Transifex: https://github.com/LLK/scratch-gui/wiki/Localization

BUT: at present (May 2020) seems like localization of extensions is not officially supported, see this Scratch GUI issue: https://github.com/LLK/scratch-gui/issues/3139

So it's best to wait for official support, unless we really need to test software in schools where children know zero English.