Support dependencies in websocket routes

I've been using dependencies to handle authentication.
But imagine my surprise when I realized my websocket endpoint wasn't authenticated at all?

This commit cherry-picks the `dependencies` chunks from `APIRoute` into `APIWebSocketRoute`

I also made a few minor style nit-picks

fastapi/applications.py

@@ -325,15 +325,35 @@ def decorator(func: DecoratedCallable) -> DecoratedCallable:
         return decorator
 
     def add_api_websocket_route(
-        self, path: str, endpoint: Callable[..., Any], name: Optional[str] = None
+        self, 
+        path: str, 
+        endpoint: Callable[..., Any], 
+        *,
+        dependencies: Optional[Sequence[Depends]] = None,
+        name: Optional[str] = None,
+
     ) -> None:
-        self.router.add_api_websocket_route(path, endpoint, name=name)
+        self.router.add_api_websocket_route(
+            path,
+            endpoint,
+            dependencies=dependencies,
+            name=name,
+        )
 
     def websocket(
-        self, path: str, name: Optional[str] = None
+        self, 
+        path: str, 
+        *,
+        dependencies: Optional[Sequence[Depends]] = None,
+        name: Optional[str] = None
     ) -> Callable[[DecoratedCallable], DecoratedCallable]:
         def decorator(func: DecoratedCallable) -> DecoratedCallable:
-            self.add_api_websocket_route(path, func, name=name)
+            self.add_api_websocket_route(
+                path,
+                func,
+                dependencies=dependencies,
+                name=name,
+            )
             return func
 
         return decorator

fastapi/routing.py

@@ -281,20 +281,27 @@ def __init__(
         path: str,
         endpoint: Callable[..., Any],
         *,
+        dependencies: Optional[Sequence[params.Depends]] = None,
         name: Optional[str] = None,
         dependency_overrides_provider: Optional[Any] = None,
     ) -> None:
         self.path = path
         self.endpoint = endpoint
+        self.dependencies = dependencies or []
         self.name = get_name(endpoint) if name is None else name
+        self.path_regex, self.path_format, self.param_convertors = compile_path(path)
         self.dependant = get_dependant(path=path, call=self.endpoint)
+        for depends in self.dependencies[::-1]:
+            self.dependant.dependencies.insert(
+                0,
+                get_parameterless_sub_dependant(depends=depends, path=self.path_format),
+            )
         self.app = websocket_session(
             get_websocket_app(
                 dependant=self.dependant,
                 dependency_overrides_provider=dependency_overrides_provider,
             )
         )
-        self.path_regex, self.path_format, self.param_convertors = compile_path(path)
 
 
 class APIRoute(routing.Route):
@@ -366,10 +373,7 @@ def __init__(
             self.secure_cloned_response_field = None
         self.status_code = status_code
         self.tags = tags or []
-        if dependencies:
-            self.dependencies = list(dependencies)
-        else:
-            self.dependencies = []
+        self.dependencies = dependencies or []
         self.summary = summary
         self.description = description or inspect.cleandoc(self.endpoint.__doc__ or "")
         # if a "form feed" character (page break) is found in the description text,
@@ -467,7 +471,7 @@ def __init__(
             ), "A path prefix must not end with '/', as the routes will start with '/'"
         self.prefix = prefix
         self.tags: List[Union[str, Enum]] = tags or []
-        self.dependencies = list(dependencies or []) or []
+        self.dependencies = dependencies or []
         self.deprecated = deprecated
         self.include_in_schema = include_in_schema
         self.responses = responses or {}
@@ -516,7 +520,7 @@ def add_api_route(
         current_tags = self.tags.copy()
         if tags:
             current_tags.extend(tags)
-        current_dependencies = self.dependencies.copy()
+        current_dependencies = list(self.dependencies)
         if dependencies:
             current_dependencies.extend(dependencies)
         current_callbacks = self.callbacks.copy()
@@ -610,21 +614,39 @@ def decorator(func: DecoratedCallable) -> DecoratedCallable:
         return decorator
 
     def add_api_websocket_route(
-        self, path: str, endpoint: Callable[..., Any], name: Optional[str] = None
+        self, 
+        path: str, 
+        endpoint: Callable[..., Any],
+        *,
+        dependencies: Optional[Sequence[params.Depends]] = None,
+        name: Optional[str] = None,
     ) -> None:
+        current_dependencies = list(self.dependencies)
+        if dependencies:
+            current_dependencies.extend(dependencies)
+
         route = APIWebSocketRoute(
             path,
             endpoint=endpoint,
             name=name,
             dependency_overrides_provider=self.dependency_overrides_provider,
+            dependencies=current_dependencies,
         )
         self.routes.append(route)
 
     def websocket(
-        self, path: str, name: Optional[str] = None
+        self,
+        path: str, 
+        *,
+        dependencies: Optional[Sequence[params.Depends]] = None,
+        name: Optional[str] = None,
     ) -> Callable[[DecoratedCallable], DecoratedCallable]:
         def decorator(func: DecoratedCallable) -> DecoratedCallable:
-            self.add_api_websocket_route(path, func, name=name)
+            self.add_api_websocket_route(
+                path,
+                func,
+                name=name,
+                dependencies=dependencies)
             return func
 
         return decorator
@@ -720,8 +742,13 @@ def include_router(
                     name=route.name,
                 )
             elif isinstance(route, APIWebSocketRoute):
+                current_dependencies: List[params.Depends] = []
+                if dependencies:
+                    current_dependencies.extend(dependencies)
+                if route.dependencies:
+                    current_dependencies.extend(route.dependencies)
                 self.add_api_websocket_route(
-                    prefix + route.path, route.endpoint, name=route.name
+                    prefix + route.path, route.endpoint, dependencies=current_dependencies, name=route.name
                 )
             elif isinstance(route, routing.WebSocketRoute):
                 self.add_websocket_route(