Support GDAL subdatasets in wcst_imports

[Dimitar Misev]

In the ingredients we can specify only proper filepaths on the file system. For some complex formats (e.g. ​netcdf), GDAL supports custom filepath schemes in order to extract subsets of the whole file, like a specific netcdf variable. We should think how this can be supported in wcst_import.

An initial idea is to support specifying pairs of (filesystem path, GDAL scheme), e.g.

"paths": [ { "file": "*.nc", "subdataset": "NETCDF:${file}:varname" } ]

[Dimitar Misev]

Is the syntax in the ticket description ok?

wcst_import still supports the old syntax of course, but in addition it would allow this so that subdatasets can be imported.

Or do you think that this can be emulated with pre-hooks which just replace the file path?

[Dimitar Misev]

So it seems like this can be now done with prehook which just replaces the path in similar way as the example in the description.

Therefore this ticket is about adding a test in the systemtest and an example in the docs.