* refactor the jmap package to split it into several files as the
jmap.api.go file was becoming too unwieldy
* refactor the Groupware handler function response to be a Response
object, to be more future-proof and avoid adding more and more
return parameters while handling "no content" response as well
* more godoc for the JMAP model
* add Email creation, updating, deleting (Email/set,
EmailSubmission/set)
* add endpoints
- POST /accounts/{accountid}/messages
- PATCH|PUT /accounts/{accountid}/messages/{messageid}
- DELETE /accounts/{accountid}/messages/{messageid}
* after having decided that the Groupware API should be a standalone
independent custom REST API that is using JMAP data models as much as
possible,
* removed Groupware APIs from the Graph service
* moved Groupware implementation to the Groupware service, and
refactored a few things accordingly
