add MapScript provider for coverages

> Hi! Yes, I mean to add this ability of using tileindex and MapScript as a source for the OGC-API Coverages collections. May be is already available as a provider?
> It will be very usefull as we have our DTM data split in different files.
> May be something like this:
>
> providers:
> - type: coverage
> name: MapScript
> data: /data/dtm_index_all.shp
> options:
> type: MS_LAYER_RASTER
> tileindex: True
> layer: sample
> format:
> name: COG
> mimetype: image/tiff; application=geotiff; profile=cloud-optimized

_Originally posted by @CeciliaPH in [#1930](https://github.com/geopython/pygeoapi/issues/1930#issuecomment-2666115760)_