Test for when an open redirect has a `http://` or `https://` prefix always added to the injected URL

[postmodern]

Test when an Open Redirect injection URL always has a http:// or https:// scheme appended to the injected value, but omitting the URI scheme from the test URL (ex: evil.com/path?id=... -> http://evil.com/path?id=). This may require adding an additional keyword argument to OpenRedirect#initialize.