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/commit_page.tmpl

@@ -72,7 +72,6 @@
 										</div>
 										<div class="content">
 											<form class="ui form" id="create-branch-form" action="" data-base-action="{{.RepoLink}}/branches/_new/commit/" method="post">
-												{{.CsrfTokenHtml}}
 												<div class="field">
 													<label>
 														{{ctx.Locale.Tr "repo.branch.new_branch_from" (HTMLFormat `<span class="%s" id="%s"></span>` "text" "modal-create-branch-from-span")}}
@@ -96,7 +95,6 @@
 										</div>
 										<div class="content">
 											<form class="ui form" id="create-tag-form" action="" data-base-action="{{.RepoLink}}/branches/_new/commit/" method="post">
-												{{.CsrfTokenHtml}}
 												<input type="hidden" name="create_tag" value="true">
 												<div class="field">
 													<label>