BUSCO graphs for assembled genomes

[grunwald]

Add BUSCO completeness to any assembled genomes.

[logankblair]

BUSCO generates its completeness plot from a companion script (scripts/generate_plot.py). Instead calling this particular script within a subworkflow, then moving images around, it may be simpler to generate a similar version within the main report R script.

[zachary-foster]

We now run busco on all eukaryotic inputs, but it is not yet run on prokaryotes. We could put it in the quality control section for prokaryotes, or do a busco phylogeny for prokaryotes as well (busco is the longest step in making a phylogeny, so might as well make a busco phylogeny if we are running busco).