first pass at adding nditer typing tests

Author: MatthieuDartiailh

numpy/typing/tests/data/reveal/nditer.py

@@ -0,0 +1,19 @@
+import copy
+import numpy as np
+
+nditer_obj: np.nditer
+
+with nditer_obj as context:
+    reveal_type(context)   # E: numpy.nditer
+
+reveal_type(len(nditer_obj))  # E: builtins.int
+reveal_type(copy.copy(nditer_obj))  # E: numpy.nditer
+reveal_type(next(nditer_obj))  # E: Any
+reveal_type(iter(nditer_obj))  # E: typing.Iterator[Any]
+reveal_type(nditer_obj[1])  # E: Any
+reveal_type(nditer_obj[1:5])  # E: Any
+
+nditer_obj[1] = 1
+nditer_obj[1:5] = 1
+del nditer_obj[1]
+del nditer_obj[1:5]