Provide a configuration option to control automatic option responses

By default Flask will provide responses to OPTIONS requests that are
automatically generated. These responses list the valid methods in the
response headers. Whilst this is useful, it can be frowned on by
auditors hence an ability to disable it wholesale is useful.

src/flask/app.py

@@ -198,6 +198,7 @@ class Flask(App):
             "PREFERRED_URL_SCHEME": "http",
             "TEMPLATES_AUTO_RELOAD": None,
             "MAX_COOKIE_SIZE": 4093,
+            "PROVIDE_AUTOMATIC_OPTIONS": True,
         }
     )
 

src/flask/sansio/app.py

@@ -638,7 +638,7 @@ class App(Scaffold):
             )
 
         if provide_automatic_options is None:
-            if "OPTIONS" not in methods:
+            if "OPTIONS" not in methods and self.config["PROVIDE_AUTOMATIC_OPTIONS"]:
                 provide_automatic_options = True
                 required_methods.add("OPTIONS")
             else: