Revisit using a stacked model with the `stacks` package

[dfsnow]

Previously, the CCAO attempted to create a stacked/ensemble model using tidymodels functions. However, tidymodels' support for this method was at the time quite new, and it didn't work very well. We should revisit using an ensemble model utilizing the relatively new stacks package.

[dfsnow]

Booting this to next year. It's complicated to implement and has a lot of downsides. Last time we tried it the performance improvement wasn't substantial. Could be a good intern or fellow project.