Allow for the creation of multiple queue items at once

This sounds like a good idea and I don't think there is a corollary in the 8.x-1.x issue queue so going to move it there. Obvsiously the existing work will need to be completely redone.

Actually we have this functionality in 8.x-1.x and we're trying to use transactions to do it properly but we've not done it right. Going to use this issue to fix it so I can credit @nvahalik for their original work here.