feat: add graphene_enum_values function & test it

might be useful because Graphene 3 has changed from using enum values to
enums, for example:

```python
class TestEnum(graphene.Enum):
  FIRST = 'first'
  SECOND = 'second'
```

would've been serialized previously using the enum values, i.e.
'first' and 'second'. But with Graphene 3 they are serialized as
'TestEnum.FIRST' and 'TestEnum.SECOND'. This breaks functionality as
parts of the codebase are expecting the enum values as per Graphene 2.

Related https://github.com/graphql-python/graphene issues & PRs:
 - "Improve enum compatibility" PR:
   - graphql-python/graphene#1153
 - "graphene3: enum doesn't resolve to value" issue:
   - graphql-python/graphene#1277
 - "I would like my enum input values to be the enum instance instead
   of the enum values" issue:
   - graphql-python/graphene#1151

refs KK-1108

common/tests/test_utils.py

@@ -0,0 +1,32 @@
+from enum import auto
+
+import graphene
+import pytest
+
+from common.utils import graphene_enum_values
+
+
+class TestGrapheneEnum(graphene.Enum):
+    FIRST_ENUM_NAME = "FIRST_ENUM_VALUE"
+    ENUM_NAME_1 = "ENUM_VALUE_1"
+    ENUM_NAME_2 = "ENUM_VALUE_2"
+    LAST_ENUM_NAME = "LAST_ENUM_VALUE"
+
+
+class TestGrapheneEnumAuto(graphene.Enum):
+    _123 = auto()
+    test = auto()
+
+
+@pytest.mark.parametrize(
+    "enum_class,expected_values",
+    [
+        (
+            TestGrapheneEnum,
+            ["FIRST_ENUM_VALUE", "ENUM_VALUE_1", "ENUM_VALUE_2", "LAST_ENUM_VALUE"],
+        ),
+        (TestGrapheneEnumAuto, [1, 2]),
+    ],
+)
+def test_graphene_enum_values(enum_class, expected_values):
+    assert graphene_enum_values(enum_class) == expected_values

common/utils.py

@@ -1,7 +1,9 @@
 import binascii
 from copy import deepcopy
 from functools import wraps
+from typing import Type
 
+import graphene
 from django.conf import settings
 from django.core.exceptions import PermissionDenied
 from django.db import transaction
@@ -144,3 +146,13 @@ def strtobool(val):
         return 0
     else:
         raise ValueError("invalid truth value %r" % (val,))
+
+
+def graphene_enum_values(enum_class: Type[graphene.Enum]) -> list:
+    """
+    Get all values of an enumeration that is derived from graphene.Enum.
+
+    :param enum_class: The enumeration class, not an instance, but the class.
+    :return: A list of all values of the enumeration.
+    """
+    return list(enum_class._meta.enum._value2member_map_.keys())