Add option for the user id sent to the external service to use Moodle Profile and Additional Profile Fields

[aspark21]

In order for the data in the external system to match up data from Moodle users consistently it would help if the data sent out could be configured to send Moodle profile / additional user profile fields so that we could for example send user email or a unique institutional identifier stored in additional profile field

"actor": {
"@id": "https:/example.moodle.site/user/4",

Looking into it, this seems to be fed from

moodle-logstore_caliper/vendor/imsglobal/caliper/src/entities/foaf/Agent.php

Line 11 in c47f923

function getId();

moodle-logstore_caliper/vendor/imsglobal/caliper/src/entities/Entity.php

Line 48 in c47f923

return $this->id;