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/repo/settings/protected_branch.tmpl

@@ -27,7 +27,6 @@
 					<p class="help tw-ml-0">{{ctx.Locale.Tr "repo.settings.protect_unprotected_file_patterns_desc" "https://pkg.go.dev/github.com/gobwas/glob#Compile" "github.com/gobwas/glob"}}</p>
 				</div>
 
-				{{.CsrfTokenHtml}}
 				<h5 class="ui dividing header">{{ctx.Locale.Tr "repo.settings.event_push"}}</h5>
 				<div class="field">
 					<div class="ui radio checkbox">