Investigate integration with file format loaders

[mvaligursky]

Loaders (and writers) library: https://loaders.gl/docs

loaders.gl is a suite of loaders for file formats focused on visualization of big data, including point clouds, 3D geometries, images, geospatial formats as well as tabular data.

DracoLoader would be a good candidate to engine example integration: https://loaders.gl/modules/draco/docs/api-reference/draco-loader (see example implementation here: #2001)

We could consider implementing engine / editor support to export entity hierarchy into glb format as well.

[mvaligursky]

marking this with good first PR.
The example should be added here and follow two loaders already there
https://github.com/playcanvas/engine/tree/master/examples/loaders