Remove generic utils import (#6764)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: Illviljan

xarray/core/indexing.py

@@ -14,12 +14,19 @@
 import pandas as pd
 from packaging.version import Version
 
-from . import duck_array_ops, nputils, utils
+from . import duck_array_ops
 from .npcompat import DTypeLike
+from .nputils import NumpyVIndexAdapter
 from .options import OPTIONS
 from .pycompat import dask_version, integer_types, is_duck_dask_array, sparse_array_type
 from .types import T_Xarray
-from .utils import either_dict_or_kwargs, get_valid_numpy_dtype
+from .utils import (
+    NDArrayMixin,
+    either_dict_or_kwargs,
+    get_valid_numpy_dtype,
+    safe_cast_to_index,
+    to_0d_array,
+)
 
 if TYPE_CHECKING:
     from .indexes import Index
@@ -431,15 +438,15 @@ class ExplicitlyIndexed:
     __slots__ = ()
 
 
-class ExplicitlyIndexedNDArrayMixin(utils.NDArrayMixin, ExplicitlyIndexed):
+class ExplicitlyIndexedNDArrayMixin(NDArrayMixin, ExplicitlyIndexed):
     __slots__ = ()
 
     def __array__(self, dtype=None):
         key = BasicIndexer((slice(None),) * self.ndim)
         return np.asarray(self[key], dtype=dtype)
 
 
-class ImplicitToExplicitIndexingAdapter(utils.NDArrayMixin):
+class ImplicitToExplicitIndexingAdapter(NDArrayMixin):
     """Wrap an array, converting tuples into the indicated explicit indexer."""
 
     __slots__ = ("array", "indexer_cls")
@@ -1234,7 +1241,7 @@ def _indexing_array_and_key(self, key):
             array = self.array
             key = _outer_to_numpy_indexer(key, self.array.shape)
         elif isinstance(key, VectorizedIndexer):
-            array = nputils.NumpyVIndexAdapter(self.array)
+            array = NumpyVIndexAdapter(self.array)
             key = key.tuple
         elif isinstance(key, BasicIndexer):
             array = self.array
@@ -1363,7 +1370,7 @@ class PandasIndexingAdapter(ExplicitlyIndexedNDArrayMixin):
     __slots__ = ("array", "_dtype")
 
     def __init__(self, array: pd.Index, dtype: DTypeLike = None):
-        self.array = utils.safe_cast_to_index(array)
+        self.array = safe_cast_to_index(array)
 
         if dtype is None:
             self._dtype = get_valid_numpy_dtype(array)
@@ -1406,7 +1413,7 @@ def _convert_scalar(self, item):
 
         # as for numpy.ndarray indexing, we always want the result to be
         # a NumPy array.
-        return utils.to_0d_array(item)
+        return to_0d_array(item)
 
     def __getitem__(
         self, indexer