Auth route /whoami for nginx subrequest auth, support changing the session cookie domain for that purpose

lib/sso_bsn_web/endpoint.ex

@@ -8,7 +8,8 @@ defmodule SsoBsnWeb.Endpoint do
     store: :cookie,
     key: "_sso_bsn_key",
     signing_salt: "2YoB6zeO",
-    same_site: "Lax"
+    same_site: "Lax",
+    domain: Application.compile_env(:sso_bsn, :session_domain)
   ]
 
   socket "/live", Phoenix.LiveView.Socket, websocket: [connect_info: [session: @session_options]]