WIP: dev for serial merging in HLT menu
development for serial merging in the HLT menu:
- create EmptyMenuSequence class, which ensures connections between filters in steps (see MenuComponents.py)
- test one chain in the emulation test having one ChainStep, containing one EmptyMenuSequence see Trigger/TrigValidation/TrigUpgradeTest/python/EmuStepProcessingConfig.py by running test_emu_step_processing.sh
Tagging @vcroft