Mbio: consider adding support for NMIT to beta div pcoa scatter plot

[d-callan]

this is a placeholder ticket to keep track of thoughts as we discuss priority and min reqs, etc.

sometimes the dimensional reduction isnt all that helpful. we could try to make it better, and an idea dan proposed to do that is to add support for nmit to the existing dimensional reduction scatter plot viz. presumably this would be something the user actively selects, and probably not on by default?

[d-callan]

from dan: