* re-implement the auth-api service to authenticate Reva tokens
following the OIDC Userinfo endpoint specification
* pass the context where necessary and add an authenticator interface
to the JMAP HTTP driver, in order to select between master
authentication (which is used when GROUPWARE_JMAP_MASTER_USERNAME and
GROUPWARE_JMAP_MASTER_PASSWORD are both set) and OIDC token
forwarding through bearer auth
* add Stalwart directory configuration "idmoidc" which uses the
OpenCloud auth-api service API (/auth/) to validate the token it
received as bearer auth from the Groupware backend's JMAP client,
using it as an OIDC Userinfo endpoint
* implement optional additional shared secret to secure the Userinfo
service, as an additional path parameter
