Add types for Flask().logger and flask.logging (#5066)

stubs/Flask/flask/app.pyi

@@ -1,4 +1,5 @@
 from datetime import timedelta
+from logging import Logger
 from types import TracebackType
 from typing import (
     Any,
@@ -104,7 +105,7 @@ class Flask(_PackageBoundObject):
     @property
     def preserve_context_on_exception(self): ...
     @property
-    def logger(self): ...
+    def logger(self) -> Logger: ...
     @property
     def jinja_env(self): ...
     @property

stubs/Flask/flask/logging.pyi

@@ -1,8 +1,12 @@
-from typing import Any
+from _typeshed.wsgi import ErrorStream
+from logging import Handler, Logger
 
-def wsgi_errors_stream(): ...
-def has_level_handler(logger: Any): ...
+from .app import Flask
 
-default_handler: Any
+wsgi_errors_stream: ErrorStream
 
-def create_logger(app: Any): ...
+def has_level_handler(logger: Logger) -> bool: ...
+
+default_handler: Handler
+
+def create_logger(app: Flask) -> Logger: ...