Add busbar data pipeline with checkpoints

• remove beam_mode/Exploration_BeamMode_for_Busbar_Nxcals.ipynb
• remove busbar/Exploration_Busbar_Nxcals_text.ipynb
• add busbar/DataPipeline_Busbar_Nxcals.ipynb that unifies beam_mode and busbar, plus adds checkpoints required for resumable/checkpointed computing
• check if lhcsmapi Python package can be added in LCG95aNXCALSpython3 LCG View to provide stable access to the API for batch jobs.
• add script to submit

@pkothuri