Refactor UserContextMiddleware to use EventContext class

This update significantly refactors UserContextMiddleware to leverage a new class, EventContext. Instead of resolving event context as a tuple, it now produces an instance of EventContext. Additional adjustments include supporting a business connection ID for event context identification and facilitating backwards compatibility. Tests and other files were also updated accordingly for these changes.

tests/test_dispatcher/test_middlewares/test_user_context.py

@@ -2,8 +2,11 @@ from unittest.mock import patch
 
 import pytest
 
-from aiogram.dispatcher.middlewares.user_context import UserContextMiddleware
-from aiogram.types import Update
+from aiogram.dispatcher.middlewares.user_context import (
+    EventContext,
+    UserContextMiddleware,
+)
+from aiogram.types import Chat, Update, User
 
 
 async def next_handler(*args, **kwargs):
@@ -18,9 +21,23 @@ class TestUserContextMiddleware:
     async def test_call(self):
         middleware = UserContextMiddleware()
         data = {}
-        with patch.object(UserContextMiddleware, "resolve_event_context", return_value=[1, 2, 3]):
+
+        chat = Chat(id=1, type="private", title="Test")
+        user = User(id=2, first_name="Test", is_bot=False)
+        thread_id = 3
+
+        with patch.object(
+            UserContextMiddleware,
+            "resolve_event_context",
+            return_value=EventContext(user=user, chat=chat, thread_id=3),
+        ):
             await middleware(next_handler, Update(update_id=42), data)
 
-        assert data["event_chat"] == 1
-        assert data["event_from_user"] == 2
-        assert data["event_thread_id"] == 3
+        event_context = data["event_context"]
+        assert isinstance(event_context, EventContext)
+        assert event_context.chat is chat
+        assert event_context.user is user
+        assert event_context.thread_id == thread_id
+        assert data["event_chat"] is chat
+        assert data["event_from_user"] is user
+        assert data["event_thread_id"] == thread_id