Add option to move closed issues to bottom of tree

Once drag-and-drop is implemented, users will be able to sort the items however they choose, but it might be useful to add an option to automatically drop closed issues & epics to the bottom of their respective lists.

For example, a nested epic with one closed issue and four open issues- the closed issue would automatically drop to the bottom of that list, not the entire tree.

We added this as a default behavior in #3695 (closed). As users are exposed to this we will gather feedback to decide if a toggle is needed.