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/shared/user/block_user_dialog.tmpl

@@ -3,7 +3,6 @@
 	<div class="content">
 		<div class="ui warning message">{{ctx.Locale.Tr "user.block.info"}}</div>
 		<form class="ui form modal-form" method="post">
-			{{.CsrfTokenHtml}}
 			<input type="hidden" name="action" value="block" />
 			<input type="hidden" name="blockee" class="modal-blockee" />
 			<div class="field">