Add step to remove overlaps

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In some rendering environments, overlaps cause issues. Specifically, the Rec Mono Code fonts are derived from the full Recursive variable font, which requires overlapping contours to interpolate to different styles. However, it should be possible to add a step to exporting which would remove overlaps, for more universal rendering.

Example of the issue, from a user:

It looks like the FontTools Instancer now has the option to remove overlaps. I’ll test this out, and if it works as I hope, this will be easy! If it doesn’t work ... this will require some more time.

https://github.com/fonttools/fonttools/blob/main/Lib/fontTools/varLib/instancer/init.py#L1182-L1192