Add count of neighboring cells

[jcssouza]

This adds the number of neighboring objects to the the function check_isolation instead of just returning true or false for a cell. The addition of this metric in the final xrarray output was suggested by Jiaxi Hu and @deeplycloudy.

[w-k-jones]

Just updated this to merging into v2.0-dev branch, which seems to have cleared up all the conflicts. I'll review and merge once I get the chance, but it all looks fine at first glance

[JuliaKukulies]

Converted this to a draft, as this change is outdated with our current development