Fix handler registration order in Scene (#1642)

* Fix handler registration order in `Scene`

Previously, `Scene` handlers were registered based on the sorted output of `inspect.getmembers`, causing incorrect execution order. Now, handlers are registered in the order they are defined in the class, ensuring reliable behavior and proper sequence when handling filters with varying specificity. Added test cases to validate the correct handler ordering.

* Add dynamic dataclass and class attribute resolvers

Introduced `dataclass_kwargs` to ensure compatibility with different Python versions and modular attribute handling. Added utilities for resolving class attributes dynamically, enhancing flexibility with MRO-based resolvers. Updated tests to verify new features and ensure proper functionality across various scenarios.

* Update changelog

CHANGES/1641.bugfix.rst

@@ -0,0 +1,20 @@
+Resolved incorrect ordering of registered handlers in the :class:`aiogram.fsm.scene.Scene`
+object caused by :code:`inspect.getmembers` returning sorted members.
+Handlers are now registered in the order of their definition within the class,
+ensuring proper execution sequence, especially when handling filters with different
+levels of specificity.
+
+For backward compatibility, the old behavior can be restored by setting the
+:code:`attrs_resolver=inspect_members_resolver` parameter in the :class:`aiogram.fsm.scene.Scene`:
+
+.. code-block:: python
+
+    from aiogram.utils.class_attrs_resolver import inspect_members_resolver
+
+
+    class MyScene(Scene, attrs_resolver=inspect_members_resolver):
+
+In this case, the handlers will be registered in the order returned by :code:`inspect.getmembers`.
+
+By default, the :code:`attrs_resolver` parameter is set to :code:`get_sorted_mro_attrs_resolver` now,
+so you **don't need** to specify it explicitly.