Fixed #31840 -- Added support for Cross-Origin Opener Policy header.

Thanks Adam Johnson and Tim Graham for the reviews.

Co-authored-by: Tim Graham <timograham@gmail.com>

tests/project_template/test_settings.py

@@ -38,6 +38,7 @@ class TestStartProjectSettings(SimpleTestCase):
             self.assertEqual(headers, [
                 b'Content-Length: 0',
                 b'Content-Type: text/html; charset=utf-8',
+                b'Cross-Origin-Opener-Policy: same-origin',
                 b'Referrer-Policy: same-origin',
                 b'X-Content-Type-Options: nosniff',
                 b'X-Frame-Options: DENY',