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/context/base.go

@@ -96,7 +96,11 @@ func (b *Base) SetTotalCountHeader(total int64) {
 
 // Written returns true if there are something sent to web browser
 func (b *Base) Written() bool {
-	return b.Resp.Status() > 0
+	return b.Resp.WrittenStatus() != 0
+}
+
+func (b *Base) WrittenStatus() int {
+	return b.Resp.WrittenStatus()
 }
 
 // Status writes status code