* move the logging of the username and session state away from pkg/jmap
and into services/groupware
* introduce more decoupling for the session cache, as well as moving
the implementation into groupware_session.go
* remove the baseurl from the JMAP client configuration, and pass it to
the session retrieval functions instead, as that is really the only
place where it is relevant, and we gain flexibility to discover that
session URL differently in the future without having to touch the
JMAP client
* move the default account identifier handling from the JMAP package to
the Groupware one, as it really has nothing to do with JMAP itself,
and is an opinionated feature of the Groupware REST API instead
* add an event listener interface for JMAP events to be more flexible
and universal, typically for metrics that are defined on the API
level that uses the JMAP client
* add errors for when default accounts cannot be determined
* split groupware_framework.go into groupware_framework.go,
groupware_request.go and groupware_response.go
* move the accountId logging into the Groupware level instead of JMAP
since it can also be relevant to other operations that might be
worthy of logging before the JMAP client is even invoked
* 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
* refactored the models to be strongly typed with structs and mapstruct
to decompose the dynamic parts of the JMAP payloads
* externalized large JSON strings for tests into .json files under
testdata/
* added a couple of fantasy Graph groupware APIs to explore further
options
* added k6 scripts to test those graph/me/messages APIs, with a setup
program to set up users in LDAP, fill their IMAP inbox, activate them
in Stalwart, cleaning things up, etc...
