Add type and direction infos in Annotation class

background issue https://github.com/Microsoft/azure-maven-plugins/issues/456

There used to be strong dependency between function maven plugin and function java library, and now we change to use java reflect to get attributes from annotation to reduce the dependency (PR https://github.com/Microsoft/azure-maven-plugins/pull/508).
However, we still need to store annotation type and direction infos in our enum class for we can't get them from annotations. So could you please add the infos in annotations of java library, like add an annotation? If so, all needed informations could comming from java library directly.
Besides, could you please update the [function.json scheme](http://json.schemastore.org/function)? Schema could be much helpful in local validation and users could verify and update their code according to schema as well

Inizia con la classe Annotation e gli enum delle annotazioni esistenti, quindi esamina la issue di contesto collegata e la pull request relativa a reflection per il contesto. Aggiorna le annotazioni Java affinché espongano le informazioni necessarie sul tipo e sulla direzione, quindi aggiorna lo schema function.json indicato affinché tali valori possano essere convalidati.

Scritto dal modello di indicizzazione a partire dal testo della issue.