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

With border board lists (those created from labels) the top border
created bad visual artifacts with the .board-inner gray border.
With this change the colored border overflows the padding-box of
.board-inner and extends to the edges.
It works very well with most colors, excepts for very light ones (such
as `#ff0` yellow for instance).

Fixes an issue in Safari that stops issues from being draggable

Closes #23048

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

Added indicator when issue detail is visible