text: Title: FeatureSet.from_geojson destroys MultiPolygons
  Body: **Describe the bug**
  Loading GeoJSON into a `FeatureSet` loses information about `MultiPolygons`. Converting back to geojson exports a `Polygon` type instead of a `MultiPolygon`.
  
  **To Reproduce**
  Steps to reproduce the behavior:
  ```python
  import json
  from arcgis.features import FeatureSet
  
  geojson_in = {'type': 'FeatureCollection',
   'features': [{'type': 'Feature',
     'geometry': {'type': 'MultiPolygon',
      'coordinates': [[[[180.0, 40.0],
         [180.0, 50.0],
         [170.0, 50.0],
         [170.0, 40.0],
         [180.0, 40.0]]],
       [[[-170.0, 40.0],
         [-170.0, 50.0],
         [-180.0, 50.0],
         [-180.0, 40.0],
         [-170.0, 40.0]]]]}}]}
  
  fs = FeatureSet.from_geojson(geojson_in)
  geojson_out = json.loads(fs.to_geojson)
  
  # geojson_out object is printed below
  {'type': 'FeatureCollection',
   'features': [{'type': 'Feature',
     'geometry': {'type': 'Polygon',
      'coordinates': [[[180.0, 40.0],
        [170.0, 40.0],
        [170.0, 50.0],
        [180.0, 50.0],
        [180.0, 40.0]],
       [[-170.0, 40.0],
        [-180.0, 40.0],
        [-180.0, 50.0],
        [-170.0, 50.0],
        [-170.0, 40.0]]]},
     'properties': {'OBJECTID': 1}}]}
  ```
  
  **Expected behavior**
  I expect a GeoJSON object that is correct. Notice how it outputs a `Polygon` object but with the polygon's rings collapsed. This has a completely different meaning.
  
  **Platform (please complete the following information):**
   - OS: MacOS
   - Browser [e.g. chrome, safari]: n/a
   - Python API Version: 2.0.0
  
  **Additional context**
  Add any other context about the problem here, attachments etc.
  