Merge pull request #15980 from Methuselah96/typescript-examples-jsm

Add TypeScript definitions for GLTFExporter

examples/jsm/exporters/GLTFExporter.d.ts

+import { Object3D } from '../../../src/Three';
+
+export class GLTFExporter {
+  constructor();
+
+  parse(input: Object3D, onCompleted: (gltf: object) => void, options: object): null;
+}