Updates/source data preferences

[abradley60]

Changes

• AUS_COP_HUB added as an option for downloaded the source scene
  • AUS_COP_HUB credentials added to example .env file
  • Download from AUS_COP_HUB requires the pygssearch package. Unfortunately, this cannot be installed in the sar-pipeline environment due to numerous package conflicts that break the workflow. The solution has been to create an additional conda environment (pygssearch-env) that gets called from a subprocess. pygssearch is a command line tool and is called as such. This new envrionment is defined in a basic envrionment-pygssearch.yaml file
• Preferential downloading from source is enabled for aqcuisition of both the scene and orbit files.
  • --scene_data_source can be one of ASF, AUS_COP_HUB, CDSE, or a space separated list of preferences
  • --orbit_data_source can be one of ASF, CDSE, or a space separated list of preferences
• Tests have been introduced for downloading files from each available option. This includes logic that enables pixi to handle the additional conda environment for pygssearch.
• Updates and renaming of docs
• Minor changes to STAC metadata

[geoscience-aman]

Thank you Alex, looking good.

[geoscience-aman]

Unrelated to this PR but can you please rename the current docs/workflows/README.MD to README.md for the link to work?

[abradley60]

Done nice pickup

[geoscience-aman]

I think the CEOS metadata spec wants the center frequency in Hz?

[abradley60]

Another conflict, the sar-extension wants it in GHz which is why I changed it. Given the xml will have us covered should I leave it?

[caitlinadams]

Thanks for adding the ability to use AusCopHub. My suggestions are minor and relate to making sure documentation is consistent with the API. The tests you've added look good to me.

[caitlinadams]

Thanks for making the changes!