Validate that geometry is fully contained in bounding volumes

[javagl]

One aspect of the validation of content data should be to check that geometry is fully contained in the relevant bounding volumes. This refers to content.boundingVolume and each tile.boundingVolume on the path from the tile that contains the geometry, up to the root.

[javagl]

A small update here: When this issue was opened, it would have been a lot of effort to actually implement this, because there was no functionality for computing the bounding volume of the tile content in the first place. In the meantime, there are some functionalities in the 3d-tiles-tools, surrounding the https://github.com/CesiumGS/3d-tiles-tools/blob/ac192defb95fde7c93a06897bf68228bd3ad87ce/src/tools/tilesetProcessing/ContentBoundingVolumes.ts#L25 class, which may allow implementing this check with reasonable effort.

It would likely be computationally expensive, so should probably be disabled by default via a validation config flag. And it could be difficult to make this check "perfect" - for example, some really clever and expensive implementation could compute a bounding volume for an I3DM that is tighter than the one that is computed with the 3D Tiles Tools. But it could at least be implemented as a preview feature, maybe even with some "threshold" so that small deviations would only be a WARNING. In any case, the building blocks are now there.