TrigT2Calo: Cleanup and remove obsolete code

This is a major cleanup of the MT-related code in the TrigT2CaloEgamma package. Many files were touched but mostly code was removed and modernized:

• Delete T2CaloEgammaFastAlgo, which was an early prototype and replaced by T2CaloEgammaReFastAlgo
• Delete some other obsolete job option files
• Python cleanup and add flake8 unit test
• Move private headers to src directory and only build a component library
• Enable static thread-safety checker

Major cleanup for the MT-base classIReAlgToolCalo:

• Remove all obsolete code
• Remove non-MT version of execute method
• Pass EventContext by reference instead of pointer in execute
• Remove error bits (not thread-safe)
• Unify code style using clang-format
• Update clients to changes and do some further cleanup.