Include tileset asset version in the url query parameter

[gkjohnson]

Related to #353

https://github.com/CesiumGS/3d-tiles/tree/main/specification#tileset-json

asset is an object containing metadata about the entire tileset. The asset.version property is a string that defines the 3D Tiles version, which specifies the JSON schema for the tileset and the base set of tile formats. The tilesetVersion property is an optional string that defines an application-specific version of a tileset, e.g., for when an existing tileset is updated.

Note The tilesetVersion can be used as a query parameter when requesting content to avoid using outdated content from a cache.

[gkjohnson]

Optionally, at least. Or expect the user to fill this in on request resolution.