smdpp_Tests/ES2Plus_Tests: move ES2+ code to smdpp_Tests.ttcn
In smdp_Tests.ttcn, the ES9+ and ES2+ interface are intermingled. This is a problem since ES2+ and ES9+ are two independed interfaces and they may use different certificates and may even be reachable under a different FQDN from a different network interface.
To untable ES2+ and ES9+ we can move the ES2+ code from ES2Plus_Tests.ttcn to smdpp_Tests.ttcn. Since ES2Plus_Tests.ttcn inherits from smdpp_Tests.ttcn the ES2+ code will still be available to ES2Plus_Tests.ttcn.
This change will add the flexibility of ES2Plus_Tests.ttcn to smdpp_Tests.ttcn. This means we can now freely configure the FQDN and the certificates used with ES2+.