[sketch] plugin should reposition artboards for new and deprecated icons

[laurenmrice]

Sketch Plugin (Icons)

• After syncing icons using the sketch plugin, the artboards need to always have equal spacing between them and be in order when icons are deprecated or added to the file.

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As-is

• There is a gap between artboards where deprecated icons have been removed.

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To-be

• There should always be equal spacing between artboards regardless if an icon has been deprecated or added to the file. This will help us to be able to scan the file better for bugs in the future and to keep all icons in order.