Feature request: Allow Cookie options (at least domain) based on incoming requests

[robaca]

We have a service serving multiple tenants with different domain names in the same process.
We'd like to set a domain part in the session cookie based on the incoming request.

We already tried creating multiple middleware instance and calling them in a wrapper middleware based on hostname, but that fails as the used cookie options are not that of the called middleware instance, but that of the last instantiated middleware.