Register cudf.core.groupby.Grouper objects to dask `grouper_dispatc…

…h` (NVIDIA#10838) (NVIDIA#10982)

Backport of rapidsai/cudf#10838

Authors:
   - https://github.com/brandon-b-miller

Approvers:
   - GALI PREM SAGAR (https://github.com/galipremsagar)
   - AJ Schmidt (https://github.com/ajschmidt8)

python/dask_cudf/dask_cudf/backends.py

@@ -296,6 +296,16 @@ def is_categorical_dtype_cudf(obj):
     return cudf.api.types.is_categorical_dtype(obj)
 
 
+try:
+    from dask.dataframe.dispatch import grouper_dispatch
+
+    @grouper_dispatch.register((cudf.Series, cudf.DataFrame))
+    def get_grouper_cudf(obj):
+        return cudf.core.groupby.Grouper
+
+except ImportError:
+    pass
+
 try:
     try:
         from dask.array.dispatch import percentile_lookup