Flowline / network pre-process.
In 01_prep, we just read in the reference flowlines. For now, that reads in a cache of reference flowlines that were created in service of this workflow. Going forward, we will be reading in a more general reference flowline network that will require some modification per #139 (closed) -- there are also quite a few outstanding issues that relate to network updates that need to be patched in here.
If possible, I want to have this issue encompass:
#130, #139 (closed), #143, #141, #140, maybe #151, and #155 (closed).
It may be that these changes need to be pushed up to the mainstems workflow reference flownetwork processes but we will need an idempotent set of checks that get executed here no matter what.