* jmap/EmailCreate: add more attributes that were omitted: Headers,
InReplyTo, References, Sender
* add jmap GetEmailSubmissionStatus
* improve email integration tests by adding a thorough test for email
submission
* jmap integration tests: provision principals and domains using the
Stalwart Management API, switching from an in-memory to an internal
directory
* fix a bug in how email summaries are flattened across multiple
accounts, which was previous resulting in empty email objects
* allow negative offset in email pagination
* make all /emails endpoints return emails without bodies
* implement Request.AllAccountIds() to generalize the fetching (and
uniqifying) of all account IDs, which will allow us to implement
things such as "subscribed" accounts, or limiting the number of
accounts in one request
* add Account-Id response header
* add Object-Type response header
* upgrade Stalwart image for devtools/full to 0.14.1
* re-assert which features are implemented or not in 0.14.1
* refactor the integration tests yet again to make it clearer and
easier to see those "features-or-not"
* get rid of old tests that are now better covered by integration tests
* rewrite how we compare expected and actual objects in integration
tests, finally having found a way to ignore the @type attribute
properly instead of having to mutate all objects to remove it
* add endpoints for Mailboxes:
- PATCH mailboxes/{id}
- DELETE mailboxes/{id}
- POST mailboxes
* refactor the pkg/jmap and groupware framework to systematically
return a jmap.State out-of-band of the per-method payloads, since
they are almost always present in JMAP responses, which lead to the
artificial creation of a lot of composed struct types just to also
return the State; on the downside, it adds yet another return
parameter
* upgrade image version in devtools to 0.14.0
* fix idmldap configuration to use the cn attribute in order for that
to also work for groups (groups don't have a uid attribute in the IDM
built-in LDAP)
* group resources are now checked against LDAP, changed
demo-principals.yaml accordingly to refer to a group that exists in
LDAP as part of the demo data
