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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

This is one step closer to making the transition to .vue files for issue boards

Aim to eventually go to vue files

Async updates the boards when searching

Fixed users href path being incorrect

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

expand remaining non-explicit eslint-disable blocks and factor out globals when no-undef encountered

Changed return statement instead of if
Delete objects after issue is closed

Closes #21219

Closes #21139