[3.12] gh-114071: [Enum] update docs and code for tuples/subclasses (GH-114871) (GH-114993)

Update documentation with `__new__` and `__init__` entries.

Support use of `auto()` in tuple subclasses on member assignment lines.  Previously, auto() was only supported on the member definition line either solo or as part of a tuple:

    RED = auto()
    BLUE = auto(), 'azul'

However, since Python itself supports using tuple subclasses where tuples are expected, e.g.:

    from collections import namedtuple
    T = namedtuple('T', 'first second third')

    def test(one, two, three):
        print(one, two, three)

    test(*T(4, 5, 6))
    GH- 4 5 6

it made sense to also support tuple subclasses in enum definitions.
(cherry picked from commit ff7588b729)

Co-authored-by: Ethan Furman <ethan@stoneleaf.us>

Lib/enum.py

@@ -457,10 +457,11 @@ class _EnumDict(dict):
             if isinstance(value, auto):
                 single = True
                 value = (value, )
-            if type(value) is tuple and any(isinstance(v, auto) for v in value):
+            if isinstance(value, tuple) and any(isinstance(v, auto) for v in value):
                 # insist on an actual tuple, no subclasses, in keeping with only supporting
                 # top-level auto() usage (not contained in any other data structure)
                 auto_valued = []
+                t = type(value)
                 for v in value:
                     if isinstance(v, auto):
                         non_auto_store = False
@@ -475,7 +476,12 @@ class _EnumDict(dict):
                 if single:
                     value = auto_valued[0]
                 else:
-                    value = tuple(auto_valued)
+                    try:
+                        # accepts iterable as multiple arguments?
+                        value = t(auto_valued)
+                    except TypeError:
+                        # then pass them in singlely
+                        value = t(*auto_valued)
             self._member_names[key] = None
             if non_auto_store:
                 self._last_values.append(value)