Fix TrigL2MuonSA/AlphaBetaEstimate.cxx to compare float valiables with ZERO_LIMIT

There are few conditional sentences like “if( (float)MiddleZ == 0. )” in AlphaBetaEstimate.cxx . To fix this, I prepared the boolean function to judge if the float values are 0 or not in AlphaBetaEstimate.h and use this to compare the float variables. I checked this code work properly in my local environment. @atlasbot @yoyamagu @sshaw @nakahama