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/forgot_passwd.tmpl

@@ -3,7 +3,6 @@
 	<div class="ui middle very relaxed page grid">
 		<div class="column">
 			<form class="ui form ignore-dirty" action="{{.Link}}" method="post">
-				{{.CsrfTokenHtml}}
 				<h2 class="ui top attached header">
 					{{ctx.Locale.Tr "auth.forgot_password_title"}}
 				</h2>