Unify update scripts across cadences

Rewrite legislator_session_update.py to follow the same structure as bill_daily_update.py
Additionally, legislator_session_update.py should transform names according to the following schema to match requested name display format:
```
Jane Doe => Doe, Jane
Jane Angelina Doe => Doe, Jane Angelina
Jane A. Doe => Doe, Jane A.
Jane Doe, M.D. => Doe, Jane, M.D.
```

techequitycollaborative / ca-leg-tracker