[pywin32] Type pscon property keys as PyPROPERTYKEY (#16656)

pywin32 converts a `PROPERTYKEY` to and from an `(IID, pid)` tuple ([source](https://github.com/mhammond/pywin32/blob/b312/com/win32comext/propsys/src/propsys.cpp#L38-L46)), and every `PKEY_*` constant in `pscon` is such a tuple ([source](https://github.com/mhammond/pywin32/blob/b312/com/win32comext/propsys/pscon.py#L153)). This makes `PyPROPERTYKEY` an alias for `tuple[PyIID, int]` and uses it for the 567 `PKEY_*` constants (plus `int` for `GUIDSTRING_MAX`/`PKEYSTR_MAX`), so the constants can be passed to `propsys` functions that take a `PyPROPERTYKEY`.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: RomanOdokienko

stubs/pywin32/_win32typing.pyi

@@ -5031,7 +5031,8 @@ class PyIViewObject2:
 
 class PyMAPINAMEIDArray: ...
 class PyOLEMENUGROUPWIDTHS: ...
-class PyPROPERTYKEY: ...
+
+PyPROPERTYKEY: TypeAlias = tuple[PyIID, int]
 
 @final
 class PyPROPVARIANT: