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/create_no_session_test.go

@@ -97,9 +97,7 @@ func TestSessionFileCreation(t *testing.T) {
 		// We're not logged in so there should be no session
 		assert.False(t, sessionFileExist(t, tmpDir, sessionID))
 
-		doc := NewHTMLParser(t, resp.Body)
 		req = NewRequestWithValues(t, "POST", "/user/login", map[string]string{
-			"_csrf":     doc.GetCSRF(),
 			"user_name": "user2",
 			"password":  userPassword,
 		})