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/org/team/teams.tmpl

@@ -25,7 +25,6 @@
 								</form>
 							{{else if $.IsOrganizationOwner}}
 								<form method="post" action="{{$.OrgLink}}/teams/{{.LowerName | PathEscape}}/action/join">
-									{{$.CsrfTokenHtml}}
 									<button type="submit" class="ui primary tiny button" name="uid" value="{{$.SignedUser.ID}}">{{ctx.Locale.Tr "org.teams.join"}}</button>
 								</form>
 							{{end}}