Run sortRequires, remove many unused modules

[mramato]

This is just some minor clean-up ahead of some ES6 work I'm going to be doing. One benefit of moving to ES6 is that unused modules will be caught by ESLint all of the time.

In fact, this is probably the last time we'll run sortRequires since it's not generally useful in non-ADM configurations.

[cesium-concierge]

Thanks for the pull request @mramato!

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[mramato]

I'll just instamerge this after CI passes.