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/settings/profile.tmpl

@@ -6,7 +6,6 @@
 		<div class="ui attached segment">
 			<p>{{ctx.Locale.Tr "settings.profile_desc"}}</p>
 			<form class="ui form" action="{{.Link}}" method="post">
-				{{.CsrfTokenHtml}}
 				<div class="required field {{if .Err_Name}}error{{end}}">
 					<label for="username">{{ctx.Locale.Tr "username"}}
 						<span class="text red tw-hidden" id="name-change-prompt"> {{ctx.Locale.Tr "settings.change_username_prompt"}}</span>
@@ -102,7 +101,6 @@
 		</h4>
 		<div class="ui attached segment">
 			<form class="ui form" action="{{.Link}}/avatar" method="post" enctype="multipart/form-data">
-				{{.CsrfTokenHtml}}
 				{{if not .DisableGravatar}}
 				<div class="inline field">
 					<div class="ui radio checkbox">