Preparing for raw banks SP

Work in progress preparatory work for raw banks SP.

Done:

• new parameter raw_banks_to_persist added to Hlt2Line() and SpruceLine()
• SelectiveCombineRawBankViewsToRawEvent is used instead of CombineRawBankViewsToRawEvent in config.py

To be done:

• ensure that everything works properly
• clean up parameters going into stream_writer (currently some redudancy)
• clean up persistency dicts within stream_writer based on new parameters

Depends on LHCb!3942 (merged)

Closes #401 (closed) #254 (closed)