Tying features to modalities in joint-RPCA

[gibsramen]

Is there a way to easily tie which feature came from which modality at the moment? As far as I can tell, the current implementation stores all features across tables in an OrdinationResults instance. You can certainly make a bespoke mapping of feature:table but I think it would be useful to incorporate this into the codebase. Specifically, this would be useful for visualization if, for example, you wanted to plot a network and color the nodes by 16S/18S/ITS/etc.