* Virtualization like core changes with intersection observer
* Virtualization like changes for spreadsheet
* Virtualization like changes for list
* Virtualization like changes for kanban
* add logic to render all the issues at once
* revert back the changes for list to follow the old pattern of grouping
* fix column shadow in spreadsheet for rendering rows
* fix constant draggable height while dragging and rendering blocks in kanban
* fix height glitch while rendered rows adjust to default height
* remove loading animation for issue layouts
* reduce requestIdleCallback timer to 300ms
* remove logic for index tarcking to force render as the same effect seems to be achieved by removing requestIdleCallback
* Fix Kanban droppable height
* fix spreadsheet sub issue loading
* force change in reference to re render the render if visible component when the order of list changes
* add comments and minor changes
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