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>

tests/integration/api_packages_container_test.go

@@ -826,7 +826,6 @@ func TestPackageContainer(t *testing.T) {
 		newOwnerName := "newUsername"
 
 		req := NewRequestWithValues(t, "POST", "/user/settings", map[string]string{
-			"_csrf":    GetUserCSRFToken(t, session),
 			"name":     newOwnerName,
 			"email":    "user2@example.com",
 			"language": "en-US",
@@ -836,7 +835,6 @@ func TestPackageContainer(t *testing.T) {
 		t.Run(fmt.Sprintf("Catalog[%s]", newOwnerName), checkCatalog(newOwnerName))
 
 		req = NewRequestWithValues(t, "POST", "/user/settings", map[string]string{
-			"_csrf":    GetUserCSRFToken(t, session),
 			"name":     user.Name,
 			"email":    "user2@example.com",
 			"language": "en-US",