Save collapsed board lists to the back end

This is a follow up issue to https://gitlab.com/gitlab-org/gitlab-ce/issues/40630. In that issue, we released the ability to collapse board lists in order to view more lists on the screen at one time. However, the collapsed list state was not saved, meaning every time a user returned to the board, they would have to re-collapse lists.

This issue saves the collapsed lists preferences to the back end for each user, providing a quality of life improvement in that your board views will now be saved for your user.

Every single list in the GitLab instance has a unique state per user.

internal customer because of same reason as in https://gitlab.com/gitlab-org/gitlab-ce/issues/40630.

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