Clean up session handling

[phirstgemini]

Need to get rid of that session_scope() function.
See https://docs.sqlalchemy.org/en/20/orm/session_basics.html#framing-out-a-begin-commit-rollback-block for how this should work. We basically want that last code block, using session.begin() as a context manager. Would be nice to have a way to emit a log message in the event that it does a rollback. Maybe also if it does a commit as it seems better to have these explicit in the code.