Edit Events API annotations
This adds the missing scope
parameter (documented in https://docs.gitlab.com/ee/api/events.html#list-currently-authenticated-users-events) for the autogenerated grape-swagger
OpenAPI documentation. It also corrects the Event.actions
value to get the keys such that they are properly captured as an enum
in the generated OpenAPI documentation (values are lost otherwise).
The OpenAPI V2 documentation will be used for dogfooding API fuzzing as per #372422 (closed) and the OpenAPI autogeneration &8926.