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>

go.sum

@@ -8,8 +8,6 @@ dario.cat/mergo v1.0.2 h1:85+piFYR1tMbRrLcDwR18y4UKJ3aH1Tbzi24VRW1TK8=
 dario.cat/mergo v1.0.2/go.mod h1:E/hbnu0NxMFBjpMIE34DRGLWqDy0g5FuKDhCb31ngxA=
 filippo.io/edwards25519 v1.2.0 h1:crnVqOiS4jqYleHd9vaKZ+HKtHfllngJIiOpNpoJsjo=
 filippo.io/edwards25519 v1.2.0/go.mod h1:xzAOLCNug/yB62zG1bQ8uziwrIqIuxhctzJT18Q77mc=
-gitea.com/go-chi/binding v0.0.0-20260819122636-082915a69981 h1:LmdlwGbzgZFZA3bK3R1q8QrNabaSz3KpnOJBLmzhN6E=
-gitea.com/go-chi/binding v0.0.0-20260819122636-082915a69981/go.mod h1:q1SSPpkC9A0gfNnoqqZ3My6kEHIpKN6QsTI+Zx73B/o=
 gitea.com/go-chi/cache v0.2.1 h1:bfAPkvXlbcZxPCpcmDVCWoHgiBSBmZN/QosnZvEC0+g=
 gitea.com/go-chi/cache v0.2.1/go.mod h1:Qic0HZ8hOHW62ETGbonpwz8WYypj9NieU9659wFUJ8Q=
 gitea.com/go-chi/captcha v0.0.0-20240315150714-fb487f629098 h1:p2ki+WK0cIeNQuqjR98IP2KZQKRzJJiV7aTeMAFwaWo=