fix: Use deepscan to detect basic code smells

[s-rigaud]

Why

Main repo Three.js started to use Deepscan website to improve their code base quality.

What

I just for this repo and tried to fix some minor code smells, mostly unusued imports.
See all the possible code smells here : https://deepscan.io/dashboard/#view=project&tid=24491&pid=27702&bid=889307&prid=&subview=issues&page=1

I didn't fix some of the most interesting ones as I don't know the expected behaviour, see issues such as this one : https://deepscan.io/dashboard/#view=project&pid=27702&iid=202651872&tid=24491&subview=issues&bid=889307

Checklist

• Documentation updated (example)
• Storybook entry added (example)
• Ready to be merged

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[joshuaellis]

I think we'd rather use eslint to solve this issue, if we update the config correctly we can avoid unused exports, i think the rest of the changes are more opinionated, but thank you for taking the time to make this PR.