Event definitions for AppSync Events

[nicklaswj]

There are currently no event definitions for the relatively new AWS AppSync Event service. Going through the AWS docs, I've collected the following list of events that could be added:

1. onPublish
2. onSubscribe
3. Lambda authorization , consisting of a authorizationRequest, authorizationContext and a authorizationReponse.
4. Optionally/debatable definitions for the event API websocket protocol messages.

I'm open to adding these myself, since I'm currently developing a system that will use AppSync Event, so I need to write them regardless.

Should these definitions live in aws_lambda_events::events::appsync (potentially in a sub-module) or in a new module aws_lambda_events::events::appsync_events ?

Edit: I've just realized that onPublish and onSubscribe only supports javascript handlers - so scratch that...