Handle Jupyter notebook stage exception individually

[AlexIoannides]

"As a ML Engineer, I would like to know why my Jupyter notebook stage has failed, so that I can fix the issue."

Tasks

• Investigate what exceptions nbconvert.preprocessors.ExecutePreprocessor().preprocess throws when a notebook raises an exception.
• Within bodywork.stage_execution.run_stage ensure that these exceptions are handled individually and that the resulting error message to the user is informative.
• Consider executing the notebook via the CLI, if this makes managing the notebook execution easier.