Enhance adhocqueue check for status report

Since per-task concurrency limits ($CFG->task_concurrency_limit) have beed introduced as part of MDL-64610 it would be good to be able to override $CFG->adhoctaskagewarn and $CFG->adhoctaskageerror for some tasks.

There is also a minor enhancement to extend Details sections to show a list of tasks when status is WARNING or ERROR.