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

Start with the Annotation class and the existing annotation enums, then review the linked background issue and reflection-related pull request for context. Update the Java annotations to expose the needed type and direction information, and update the referenced function.json schema so those values can be validated.

Written by the indexing model from the issue text.