Typed data (#1647)

* Add TypedDict support for middleware context data

Introduced `MiddlewareData` and associated TypedDicts to type-hint middleware context data. Updated documentation to include usage examples and guidelines for extending the default middleware data. Also adjusted coverage configuration to exclude the new data module.

* Added more docstrings

* Typo fixes

pyproject.toml

@@ -261,7 +261,8 @@ filterwarnings = [
 branch = false
 parallel = true
 omit = [
-    "aiogram/__about__.py",
+    "aiogram/__meta__.py",
+    "aiogram/dispatcher/middlewares/data.py"
 ]
 
 [tool.coverage.report]