JSDoc: Add import section for addons.

[Mugen87]

Related issue: -

Description

The PR adds the following section to doc pages:

We had this in place for the old docs and it seems it was a helpful feature for users. The only problem is we can't generate the section automatically since addons are not imported in a uniform fashion. E.g.

import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
import GLSLDecoder from 'three/addons/transpiler/GLSLDecoder.js';
import * as BufferGeometryUtils from 'three/addons/utils/BufferGeometryUtils.js';

So the idea is to use a custom tag @three_import to classes and modules which documents the import. If we agree on that, I can file a follow-up PR updating all addons.

[mrdoob]

That sounds good to me 👌