Added suppport for geotiff colormap() colorinterp to be loaded into attrs

[alando46]

This is tangentially related to the to_geotiff() discussion.

We're using intake-xarray to read a year's worth of Sentinel-2 Scene Classification Layers into a DataArray, doing some processing, and then writing the output to a single band GeoTIFF. When writing the output, we'd like to preserve the colormap of the original underlying data. xarray-intake uses xarray to read the dataset, so thought it might be useful to add support in open_rasterio() to read and load src.colormap(1) and src.colorinterp into the attributes of the DataArray. My thinking is that if in the future the community ends up wanting to add a to_geotiff() method, reading the src colormap and colorinterp might be useful.

Before adding tests, I thought I'd submit the PR to see what others thought about adding this functionality. If there's support for this, I'm happy to add any needed tests or documentation.

• Tests added
• Fully documented, including whats-new.rst for all changes and api.rst for new API

[codecov]

Codecov Report

Merging #3136 into master will decrease coverage by 0.94%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master    #3136      +/-   ##
==========================================
- Coverage   95.99%   95.05%   -0.95%     
==========================================
  Files          63       63              
  Lines       12799    12803       +4     
==========================================
- Hits        12287    12170     -117     
- Misses        512      633     +121

[dcherian]

I think we'd like to load all possible attrs and make them accessible if it's easy to do so.

Is there a way to do that without having to explicitly add each one?

[alando46]

@dcherian that makes sense to me and shouldn't be difficult to do. I basically just tried to follow the existing design pattern for the other attributes.

[keewis]

related to #4697: now that we consider deprecating xr.open_rasterio in favor of xr.open_dataset(..., engine="rasterio") (implemented by rioxarray), should this be moved there?

[snowman2]

Related: corteva/rioxarray#191

[dcherian]

Should be fixed in rioxarray since we've now deprecated open_raserio.