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/diff/comment_form.tmpl

@@ -1,6 +1,5 @@
 {{if and $.root.SignedUserID (not $.Repository.IsArchived)}}
 	<form class="ui form {{if $.hidden}}tw-hidden comment-form{{end}}" action="{{$.root.Issue.Link}}/files/reviews/comments" method="post">
-	{{$.root.CsrfTokenHtml}}
 		<input type="hidden" name="origin" value="{{if $.root.PageIsPullFiles}}diff{{else}}timeline{{end}}">
 		<input type="hidden" name="latest_commit_id" value="{{$.root.AfterCommitID}}">
 		<input type="hidden" name="side" value="{{if $.Side}}{{$.Side}}{{end}}">