added FED 793 to the list of the RPC FEDs
runcontrol/src/common/FEDMap.cc: adding FED 793 in the FEDMap::isEnabled method. 793 is an "artificial" FED for sending the RPC TTS status. It is needed to add this FED here because the other RPC FEDs (790, 791, 792) might be disabled, but the FED 793 still will be used. In this case, without the FED 793 in the FEDMap::isEnabled, in the central cell method RunControl::execStart() the SynchronizeLinksCommand will not be executed. Then the RPC links to the OMTF, CPPF, and TwinMux will not work.