Refactor web package and context package (#25298)

1. The "web" package shouldn't depends on "modules/context" package,
instead, let each "web context" register themselves to the "web"
package.
2. The old Init/Free doesn't make sense, so simplify it
* The ctx in "Init(ctx)" is never used, and shouldn't be used that way
* The "Free" is never called and shouldn't be called because the SSPI
instance is shared

---------

Co-authored-by: Giteabot <teabot@gitea.io>

modules/web/types/response.go

@@ -0,0 +1,10 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package types
+
+// ResponseStatusProvider is an interface to get the written status in the response
+// Many packages need this interface, so put it in the separate package to avoid import cycle
+type ResponseStatusProvider interface {
+	WrittenStatus() int
+}