Replace CSRF cookie with CrossOriginProtection (#36183)

Removes the CSRF cookie in favor of
[`CrossOriginProtection`](https://pkg.go.dev/net/http#CrossOriginProtection)
which relies purely on HTTP headers.

Fixes: https://github.com/go-gitea/gitea/issues/11188
Fixes: https://github.com/go-gitea/gitea/issues/30333
Helps: https://github.com/go-gitea/gitea/issues/35107

TODOs:

- [x] Fix tests
- [ ] Ideally add tests to validates the protection

---------

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

templates/user/auth/change_passwd_inner.tmpl

@@ -6,7 +6,6 @@
 		</h4>
 		<div class="ui attached segment">
 			<form class="ui form tw-max-w-2xl tw-m-auto" action="{{.ChangePasscodeLink}}" method="post">
-			{{.CsrfTokenHtml}}
 			<div class="required field {{if and (.Err_Password) (or (not .LinkAccountMode) (and .LinkAccountMode .LinkAccountModeSignIn))}}error{{end}}">
 				<label for="password">{{ctx.Locale.Tr "password"}}</label>
 				<input id="password" name="password" type="password" value="{{.password}}" autocomplete="new-password" required>