[3D Tiles] multiple contents support, v. 1.1 support

[andreasplesch]

From what I can tell the 3D tiles loader may not currently support "multiple contents", a feature available in 3D Tiles v. 1.1 (https://github.com/CesiumGS/3d-tiles?tab=readme-ov-file#version-history) which was promoted from an extension in v. 1.0.

I found

loaders.gl/modules/3d-tiles/src/lib/parsers/helpers/parse-3d-implicit-tiles.ts

Line 273 in d74df44

/** TODO: we don't support `3DTILES_multiple_contents` extension at the moment.

which seems current.

Some features of v. 1.1 are supported, such as glTF content without an extension.

I found this table for the converter: https://github.com/visgl/loaders.gl/blob/master/docs/modules/tile-converter/cli-reference/supported-features.md?plain=1

It was last updated 2 years ago. Is is applicable to the loader in general and does it represent the status of v.1.1 support ?

Thanks.