Add a helper class to access Elevation service

[sherylgiovanni]

Describe the problem

With the new Elevation service, it would be nice to have a REST JS helper class so that we don't need to do a raw fetch call to the service endpoint everytime. This would greatly help writing the code for other open source libraries such as Leaflet, OpenLayers, MapLibre, etc where we don't need to do a raw fetch call. Something like arcgisRest.findElevationAtPoint and arcgisRest.findElevationAtManyPoints would be great.

Describe the proposed solution

I would like to see a helper class to access the new elevation service. The service has two endpoints, GET at-point and POST at-many-points. We can also choose whether to get an elevation value relative to meanSeaLevel or ellipsoid.

I would like to help with this. How do I create a new package? Do I just do something like https://github.com/Esri/arcgis-rest-js/tree/main/packages and try to mimic the structure of the other existing packages and create a PR?

Additional Information

cc @patrickarlt @gavinr-maps @gavinr

[patrickarlt]

@sherylgiovanni Mostly you would follow something like https://github.com/Esri/arcgis-rest-js/pull/1103/files which is where we added the places package. Elevation would be similar but we are trying to move the demos to a separate repo and you probably don't need to make any changes to the request package.

You can setup a meeting with myself and Gavin to discuss.