Add direction coordinates to CONUS404 wind dataset

[orianac]

Change number-based indexing to direction indexing by adding coordinates to CONUS404 wind dataset. This would remove the need for us to define them in the fire.py module like here. It would also then ensure alignment in the analysis like in the definition of the plot_regions_two_datasets function in the compare-risk-raster.ipynb notebook (see comment from @badgley in #324)

[norlandrhagen]

@orianac for label