Consider eliminating IP and port based tenant config

Currently edge-sip2 relies on config file to know which tenant is from which IP (and port). There have been some hosting challenges with this approach. For examples, it is difficult to preserve accurate client IP with VPC traffic inspection; it is cumbersome to use multiple custom ports and poses potential security risk. Since sip2 client does the login when creating the connection to edge-sip2, maybe edge-sip2 can determine the tenant based on the login info provided by the client? If the login info only contains username and password, one possibility is for edge-sip2 to try the login with all tenants or some predefined tenant list to see which tenant the connection is for. If this is doable, it will greatly simplify edge-sip2 hosting and improve the security.