De-duplicate historic vs fetch/process fxns

[lindsayplatt]

I built this pipeline so that the historic download component is completely separate. During that development, I decided to duplicate fxns but name them with _historic so that I wouldn't have to worry about tiny changes in the fetch/process components causing a rebuild of the historic data.

As Cee points out here, that was not the best idea because it sets us up for potential future issues with changing one but forgetting to change the other. I should go through and de-duplicate those shared functions to clean this workflow up.

Here's my plan for tackling:

• Make a list/table of the duplicate fxns
• Create a shared fxn file
• Rebuild both historic and the current dates with the new shared fxns