Suggested Updates to SnowEx notebook

[andypbarrett]

After reviewing Snow Depth and Snow Cover Data Exploration notebook, I'm suggesting the following updates and changes.

These changes will address the move of data and decommissioning of ECS, as well as bring the notebook up to date to use modern tools and approaches.

1. Use earthaccess to search and access datasets.
   a. Use separate calls to earthaccess rather than looping through a dictionary. If we use a dictionary, we have to explain dictionaries and loops.
2. Use Geopandas to find temporally and spatially coincident data granules.
3. Use xarray and rioxarray to open and transform MOD10A1 granule, also ASO granule. This also allows xarray's interpolation/resampling functions to be used.
4. Define ROI polygon in notebook rather than using JSON. There is a missing step of how to generate the GeoJSON or how to define the polygon.
5. Use harmony-py to subset MODIS