Limit concurrency of IIIF fetches on our OSD implementation #490
Description
What?
A large manifest can basically have thousands of images. A single client will basically *with current code * try to fetch via async as many images it can, sometimes hitting our NGINX Bot Blocker. Also performance wise, given that image might be a sequence of a single HUGE PDF, that is terrible
I really like this approach (not that I have free time to do more but ...)