refactor: move go-chi/binding into Gitea (#39528)

The `gitea.com/go-chi/binding` package only exists for Gitea, so it
moves into `modules/web/binding` to fix its bugs directly. Split out of
https://github.com/go-gitea/gitea/pull/39504.

- GET and HEAD always bind the query
- JSON `null` slice elements and nested `TrimSpace` fields bind
correctly
- Integer fields reject out-of-range values instead of wrapping
- An empty JSON body binds nothing and an unknown binding rule is an
error

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: bircni <bircni@icloud.com>

services/forms/repo_form.go

@@ -350,7 +350,7 @@ type CreateIssueForm struct {
 type CreateCommentForm struct {
 	middleware.FormDefaultValidator
 	Content string
-	Status  string `binding:"OmitEmpty;In(reopen,close)"`
+	Status  string `binding:"In(reopen,close)"`
 	Files   []string
 }
 
@@ -571,12 +571,6 @@ type AddTimeManuallyForm struct {
 	Minutes int `binding:"Range(0,1000)"`
 }
 
-// SaveTopicForm form for save topics for repository
-type SaveTopicForm struct {
-	middleware.FormDefaultValidator
-	Topics []string `binding:"topics;Required;"`
-}
-
 // AddDeployTokenForm form for adding a deploy token to a repository
 type AddDeployTokenForm struct {
 	middleware.FormDefaultValidator