bpo-38659: [Enum] add _simple_enum decorator (GH-25285)

add:

_simple_enum decorator to transform a normal class into an enum
_test_simple_enum function to compare
_old_convert_ to enable checking _convert_ generated enums
_simple_enum takes a normal class and converts it into an enum:

@simple_enum(Enum)
class Color:
    RED = 1
    GREEN = 2
    BLUE = 3

_old_convert_ works much like _convert_ does, using the original logic:

# in a test file
import socket, enum
CheckedAddressFamily = enum._old_convert_(
        enum.IntEnum, 'AddressFamily', 'socket',
        lambda C: C.isupper() and C.startswith('AF_'),
        source=_socket,
        )

test_simple_enum takes a traditional enum and a simple enum and
compares the two:

# in the REPL or the same module as Color
class CheckedColor(Enum):
    RED = 1
    GREEN = 2
    BLUE = 3

_test_simple_enum(CheckedColor, Color)

_test_simple_enum(CheckedAddressFamily, socket.AddressFamily)

Any important differences will raise a TypeError

Lib/pstats.py

@@ -26,14 +26,15 @@ import time
 import marshal
 import re
 
-from enum import Enum
+from enum import StrEnum, _simple_enum
 from functools import cmp_to_key
 from dataclasses import dataclass
 from typing import Dict
 
 __all__ = ["Stats", "SortKey", "FunctionProfile", "StatsProfile"]
 
-class SortKey(str, Enum):
+@_simple_enum(StrEnum)
+class SortKey:
     CALLS = 'calls', 'ncalls'
     CUMULATIVE = 'cumulative', 'cumtime'
     FILENAME = 'filename', 'module'