Project/Dataset export import API alignment

[igor-davidyuk]

Introduce methods for importing and exporting project and dataset snapshots following the web UI functionality.

[ljcornel]

Great work, thanks a lot!

Aside from a couple of minor remarks, one thing I'm still missing is the documentation for the new methods. I'm not sure what the best place to add this is, but I'd like to see a short list of the methods we have now for up/download, along with a short description. I think having an overview like that somewhere would help users to select the method appropriate for their use case.

Maybe we can add it to the import/export module init? That way it should be easy to include it in the sphinx documentation as well.

[igor-davidyuk]

Maybe we can add it to the import/export module init? That way it should be easy to include it in the sphinx documentation as well.

The IE module does not expose these methods. Instead, I added the description for all the methods to the Geti module docstring.