CT15: Request over class 3 with same sequence count needs to trigger (re)production of the previous response

These requirements were not tested previously by the Conformance Test, but are now part of CT15.

According to specification Vol1. Figure 3-4.5, reception of UnitData with the same sequence count value should retrigger sending the response to the previous request (the one which initally had that particular sequence count value), instead of being dispatched towards the message router towards the object dictionary.

This can be implemented by skipping the swapping of the receive buffer with the CL3 in-place buffer and instead resending the contents of the CL3 in-place buffer which still contains the exact reply which has been generated for the previous service request processed for that CL3 connection.

We just need to keep track of the last sequence count value for each CL3 connection and factor out and hook a subset of the EipEncapCl3_SendResponse() function.