MINOR: tasks/debug: add a few BUG_ON() to detect use of wrong timer queue

MINOR: tasks/debug: add a few BUG_ON() to detect use of wrong timer queue

This aims at catching calls to task_unlink_wq() performed by the wrong
thread based on the shared status for the task, as well as calls to
__task_queue() with the wrong timer queue being used based on the task's
capabilities. This will at least help eliminate some hypothesis during
debugging sessions when suspecting that a wrong thread has attempted to
queue a task at the wrong place.