When a question bank is restored along with a quiz that uses a random question from that bank,
the set reference for the random question should now point to the category in the restored bank,
rather than original.
This uses the question bank context IDs recorded using the method added in MDL-86136
to decide if the set reference's question context is being restored, and update it
accordingly.
This required adding a new restore step in the restore_root_task, since when a restore is
performed asynchronously, the temp IDs table is deleted after the prechecks are performed
when the task is queued. Adding this step allows the IDs to be recorded again when the restore
runs.
Mark Johnson
1890a0b94d