refactor: http request binding (#38971)

Better than before, still not good enough (more work can be done in the
future)

And add the missing error handling in the PrivateContext "bind"
middleware.

By the way, picked some "TrimSpace" changes from "fix: trim whitespace
from SMTP address and port - #38934" (fix #38926)

routers/web/web.go

@@ -20,7 +20,6 @@ import (
 	"gitea.dev/modules/setting"
 	"gitea.dev/modules/storage"
 	"gitea.dev/modules/structs"
-	"gitea.dev/modules/validation"
 	"gitea.dev/modules/web"
 	"gitea.dev/modules/web/middleware"
 	"gitea.dev/modules/web/routing"
@@ -345,8 +344,6 @@ func addProjectBoardRoutes(m *web.Router) {
 
 // registerWebRoutes register routes
 func registerWebRoutes(m *web.Router, webAuth *AuthMiddleware) {
-	validation.AddBindingRules()
-
 	// middleware: required to be signed in or signed out
 	reqSignIn := verifyAuthWithOptions(&common.VerifyOptions{SignInRequired: true})
 	reqSignOut := verifyAuthWithOptions(&common.VerifyOptions{SignOutRequired: true})