Add Google Satellite Embeddings data source

[favyen2]

Add Google Satellite Embeddings data source. It is a subclass of GEE.

Depends on #178 since there are some changes to RasterFormat there.

Associated changes:

• GEE: some updates to split up export so it is easier to override, and had to pass maxError to image.geometry().transform(...) since GEE was complaining about that being missing.
• Raster directory: if the name is too long when doing "_".join(bands), then use hash of the bands instead.

Miscellaneous changes that got included here:

• Change retry log message from debug to warning. It is confusing when the error is not displayed, I think it should be warning.
• Allow prepare/ingest/materialize to specify list of groups instead of only accepting a single group.