Refactor the setting of collectionID

[siiriylonen]

No description provided.

[demiankatz]

Thanks, @siiriylonen. I'd be interested to hear a little more about how you plan to use this, just in case there are any further changes needed to fully support your use case. In any case, assuming there is definitely a need for this change, I made a couple of suggestions below that might further improve upon it.

[siiriylonen]

The intent would be just to make this value easier to customise.
If you mean the further use, it would be then modified to test, if changing the CollectionList tab’s display is something worth doing. (Relating to the closed pr about showing all the items on all archive levels, but at the cost of losing hierarchy structure, so not really a fully functional solution anyway.)

[demiankatz]

Thanks, @siiriylonen, this looks good to me! I'm just going to wait to merge until I hear if @EreMaijala has any further input to share.