Edits to ZDC signal processing in preparation for analysis of data from LHCf run

• ForwardDetectors/ZDC/ZdcAnalysis/ZdcAnalysis/ZDCPulseAnalyzer.h and
• ForwardDetectors/ZDC/ZdcAnalysis/Root/ZDCPulseAnalyzer.cxx

implement more general setting of high gain and low gain multiplicative factors

• ForwardDetectors/ZDC/ZdcAnalysis/ZdcAnalysis/ZDCDataAnalyzer.h and
• ForwardDetectors/ZDC/ZdcAnalysis/Root/ZDCDataAnalyzer.cxx

support the above (ZDCPulseAnalyzer gain factor modifications)

• ForwardDetectors/ZDC/ZdcAnalysis/Root/ZdcAnalysisTool.cxx

Optimize the LHCf run configuration (use "Run3" pulse fit function, set better default T0 values, improved cuts, set to use low-gain samples by default)

• ForwardDetectors/ZDC/ZdcRec/src/ZdcRecChannelToolLucrod.cxx

Switch side C numbering to -1 (as it should be) when using Run 3 data.