Support for API ML cookie using cookie identifier

[pablocarle]

Describe the bug

This was already discussed in the squad meeting, but opening here to have a place to follow-up on it. API ML introduced support for an instance-based cookie identifier for the authentication cookie apimlAuthenticationToken, described here: https://docs.zowe.org/stable/user-guide/api-mediation/api-gateway-configuration/#unique-cookie-name-for-multiple-zowe-instances

It works somewhat differently than the zss session implementation of similar feature, in that it has its own parameter in zowe.yaml: components.gateway.apiml.security.auth.uniqueCookie

This is scheduled for 2.9, as the version released in 2.8 has a known bug, where if set API ML will not work properly.