Add cluster expansion zoom for clustered MTS tilesets

Nobody has claimed this yet.

## Motivation

Being able to click into clustered points when using a clustered MTS tileset like the `.getClusterExpansionZoom` function supported for a geojson source.

https://docs.mapbox.com/mapbox-gl-js/example/cluster/#:~:text=getClusterExpansionZoom

## Design

Clicking a clustered point would either reveal the next batch of clustering, or if there are no more clusters then reveal the features.

Currently, you either have to zoom straight into the features (potentially bypassing other clusters), or incrementally zoom in which means the customer clicking on the same cluster multiple times. Therefore, the advantage of this approach is improving customer experience when clicking on clusters.

This approach works really well with `.getClusterExpansionZoom` for geojson sources so it would be good to see it available for MTS tilesets as well.

Start by reviewing the existing getClusterExpansionZoom behavior for GeoJSON sources and the linked clustering example, then compare it with clustered MTS tilesets. Done means defining and implementing equivalent expansion behavior that reveals the next cluster or the underlying features when no clusters remain.

Written by the indexing model from the issue text.