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)

modules/web/router.go

@@ -15,33 +15,26 @@ import (
 	"gitea.dev/modules/reqctx"
 	"gitea.dev/modules/setting"
 	"gitea.dev/modules/translation"
+	"gitea.dev/modules/validation"
 	"gitea.dev/modules/web/middleware"
 	"gitea.dev/modules/web/types"
 
-	"gitea.com/go-chi/binding"
 	"github.com/go-chi/chi/v5"
 )
 
 // Bind binding the request form to a form object and assign context data
-func Bind[T interface {
-	*E
-	middleware.Form
-}, E any]() http.HandlerFunc {
+func Bind[T middleware.Form]() http.HandlerFunc {
 	return func(resp http.ResponseWriter, req *http.Request) {
+		form, errs := middleware.BindFormValidate[T](req, validation.Binder())
+
 		ctx := reqctx.FromContext(req.Context())
 		data := ctx.GetData()
 		locale := ctx.Value(translation.ContextKey).(translation.Locale) //nolint:forcetypeassert // must exist
-
-		obj := new(E)
-		var form T = obj
-		vctx := &middleware.ValidateContext{Locale: locale, Data: data, Req: req, Resp: resp}
-		errs := binding.Bind(req, obj)
-		errs = form.Validate(vctx, errs)
-		SetForm(data, obj)
+		SetForm(data, form)
 
 		// Legacy template error handling: try to restore the form's values as much as possible,
 		// especially for RenderWithErrDeprecated to re-render the form with errors.
-		middleware.AssignForm(obj, data)
+		middleware.AssignForm(form, data)
 		errorMessage, errorFieldName, _ := middleware.BuildValidationErrorForUser(form, locale, errs)
 		if errorMessage != "" {
 			data["HasError"] = true