TrigT1CaloSim athenaMT migration: JetCMX

Part 2 in a slowly progressing series of merge requests to adapt TrigT1CaloSim (Run-2 L1Calo simulation) algorithms to athenaMT. In this MR, the JetCMX algorithm is adapted with the following changes:

1. Replace JetCMX direct SG access with ReadHandles and WriteHandles.
2. Make JetCMX a re-entrant algorithm with a const execute method.
3. Use smart pointers instead of new everywhere.

Tested by running test_trig_mc_v1Dev_L1SimOnly_build.py before and after changes, and comparing the outputs with rootcomp (online histograms) and diff-root (RDO_TRIG POOL output). The outputs were identical in both checks.

Relevant Jira tickets are: ATR-17916 and ATR-20535

Previous MRs:

• EnergyCMX: !35483 (merged)

FYI @afaulkne, @smh