Proto: refactor the [process_backlog] functions
requested to merge lthms/tezos:lthms@oru-process-backlog-refactor into ulrikstrid@blst-sig-rollups-pick
We propose several changes to the current implementation of [process_backlog] and its companion functions.
- We try to remove redundant [get_rollup] calls
- We provide docstrings for key functions involved in this process
- We propose aesthetic refactoring to improve the readability
- We identify one potential error in the implementation with a [FIXME] comment and a rationale