Implement additional python-based integration methods

[nictru]

scIB contains a lot of directly usable implementations for integration methods. It should be fairly easy to implement them based on the functions provided in this script.

Integration methods to implement

• [x] scanorama
• [ ] trvae
• [x] trvaep
• [x] scgen
• [x] bbknn
• [ ] saucie
• [x] combat
• [x] desc

Integration methods to standardize

We already have some integration methods available in our pipeline. They should also be using the scIB package so that we have the same structure for all the integration methods.

• [x] scVI
• [x] scANVI
• [x] MNN

[nictru]

The following packages have dependency problems and could not easily be implemented by now:

• trvae (not a problem because trvaep is just another implementation of it)
• saucie

[nictru]

Seurat integration would be very valuable but can not be implemented using scIB since it is a pure R package. Maybe @serareif could have a look at this?

[nictru]

There are multiple R-based integration methods, created separate issue for this (#18)