Improve shapefile subsetting performance

[skorper]

Investigate possible performance improvements to the shapefile subsetting capability. This capability is currently being brute-forced, but there might be a more elegant solution. Because this is L2 data, many of the existing capabilities for doing this may not work, such as using rioxarray.

The following library may be useful in achieving this: https://github.com/xarray-contrib/xoak
Also, see the the following discussion on this exact topic: corteva/rioxarray#202

[jamesfwood]

Moved to this issue:
#316