Make a new repo for Metrics Paper

[jds485]

This repo is large and most of it sets up attributes and flow metrics that we'll develop models to predict in the Metrics Paper. I think we could create a new repo with only flow metric prediction functions and targets, and keep this repo as a data prep + seasonal high flow regions repo. I think that will save us time for the next paper.

Could also create a Docker container for the flow metrics repo that is separate from this repo to prevent issues like we saw with packages being updated for the same version of R