While deep nesting will not work on a standard `<select>`, we can
emulate it through data objects still, and just handle the display
of the data in the results.
This also means that the horrific deep-nested CSS is back to handle
the padding. I hope that will get fixed over time.
This also fixes one of the performance issues with adding array
data, as options are added at the very end instead of one by one.
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