Add tool for reconstructing ET sums in data. Add overflow checks to eEM and eTAU algorithms.

The main purpose of this merge is to add a tool that allows the user to reconstruct the various jet discriminant sums for an eEM or eTAU trigger object (TOB). These are important for optimising the trigger configuration, but not read out as part of the TOB (would require 3 extra words/TOB to do so), so need to be reconstructed and added as decorations to the EDM. These tools are in a new class, LVL1::TOBEtTool, plus its virtual interface.

Adding these tools required adding new getters to the eFEXegAlgo and eFEXtauAlgo classes (simulation classes used to reconstruct the sums). These new getters are not used in the simulation, so do not change any existing data flow.

As part of the testing I discovered that the simulation was not limiting the word lengths for the ET sums to 16 bits as the hardware does. This would not affect simulation of trigger thresholds, but does mean that MC TOBs could contain incorrect ET values when saturation occurs (i.e. saturated isolation sums appearing unsaturated). The merge therefore corrects this behaviour