Add SANSA model ("sparse EASE")

[matospiso]

Hi, I'm one of the authors of SANSA and we'd like to ask you if we could add our model to your framework.

The official implementation of our model is open-source and we've recently released it as a package. Therefore, it will be relatively straight-forward to write an interface similar to how it's done for EASE, except that the core (training) would just be a call of a function from our package. We'll be happy to create a pull request, just let us know if you have some instructions/requirements for us :)

There is one non-standard dependency, though -- a numerical library SuiteSparse. Our readme describes how to install it and "link it" for the package installation. I think the easiest way would be to include our package in optional requirements (in pyproject.toml), and describe the need for installation of SuiteSparse as a prerequisite to our package in readme (the details should just point to our readme where it should be explained).

Let me know what you think, thanks! :)