Validator - Check that BATCH_ID values are correct

[lilleyse]

@rms13

i3dm and pnts tiles contain an optional BATCH_ID semantic in their feature table. If this property exists, its values should be less than BATCH_LENGTH.

To help parse the contents of a feature table, you can require Cesium's Cesium3DTileFeatureTable file similar to how defined and defaultValue are often required.

Later we will also check that the batch id values for a b3dm tile are in range, but that won't be ready until we can parse embedded glb's.

[rms13]

@lilleyse Should the BATCH_IDs be less than BATCH_LENGTH or exactly equal?

[lilleyse]

They should be less than.