Closes #35296

Added by
https://gitlab.com/gitlab-org/gitlab-ee/commit/88aea2cbc8633ba970335d935d725bd17654b424

Part of this MR: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1797/

[ci skip]

fix some false positive tests for board_new_issue

The closed & backlog lists in issue boards are no collapsible. They can
be collapsed independently of each other & this selection is then saved
to the browser through localStorage. When the page loads, the code gets
the data from localStorage & determines whether to show or hide the list

Closes #23917

Closes #30209

Closes #30123

Clean up the events when the modal window is closed

[ci skip]

Added some error handling which reverts the frontend data changes &
notifies the user

Does not remove the issue from the selected tab when it it de-selected, it instead gets purged when changing tab

Changed what is hidden when data is loading

Adds issues to list on frontend - need to push to backend

Submit button disables/enables
Submit button selects ids - but does not push it yet

Possibly need to change masonry library but so far it is the only one I found that works well

This removes the backlog list & instead creates a modal window that will
list all issues that are not part of a list for easy adding onto the
board

Closes #26205

Changed CSS transition property for only values that change

- Adds animation when opening & closing the sidebar
- Adds an animation when dragging boards to a new position
- Adds animations to dragging issues around

When opening the sidebar it will also animate the scrollLeft property to
make moving to the opened issue less blunt.

Closes #25630