SameSite cookie attribute missing from session cookies

[madmatt]

This leads to issues when attempting to use the RealMeBackURL value to redirect users. This value is stored in session but in browsers like Chrome 80+ that don't sent session cookies when returning from RealMe, this gets lost and the session is re-created when the user returns from RealMe, losing the BackURL.

We've solved this for version 2.1.0 of the module (see changes here and here) - this issue is to track the resolution for the currently active version (v4).