migrate to S7 #271
Description
A lot of bugs are introduced due to missing type checks or expected fields etc. To prevent this, i think the arcgis metapackage should begin to migrate to S7 classes for each primary type of object we work with. Much of this ought to probably be done first in arcgisutils first.
There are a number of object representations that arcgis services use and having consistent type checking for each of these would be a huge win and huge simplification.
Most of these are defined at:
https://developers.arcgis.com/rest/services-reference/enterprise/featureset-object/
Then there are things like the FeatureLayer or FeatureServer custom s3 classes that may need to be migrated.
This will also help with managing parameters etc.