Refactor auth middleware (#36848)

Principles: let the caller decide what it needs, but not let the
framework (middleware) guess what it should do.

Then a lot of hacky code can be removed. And some FIXMEs can be fixed.

This PR introduces a new kind of middleware: "PreMiddleware", it will be
executed before all other middlewares on the same routing level, then a
route can declare its options for other middlewares.

By the way, allow the workflow badge to be accessed by Basic or OAuth2
auth.

Fixes: https://github.com/go-gitea/gitea/pull/36830
Fixes: https://github.com/go-gitea/gitea/issues/36859

routers/api/actions/artifacts.go

@@ -103,7 +103,7 @@ func init() {
 
 func ArtifactsRoutes(prefix string) *web.Router {
 	m := web.NewRouter()
-	m.Use(ArtifactContexter())
+	m.AfterRouting(ArtifactContexter())
 
 	r := artifactRoutes{
 		prefix: prefix,