[Metagenomics wf] capture and report MAG coverage across samples

[AstrobioMike]

• contig-level coverage is already generated and provided for individual samples, but that would only include the MAGs from that sample
• should make a combined bowtie2 db of all MAGs and then map each sample to that to get MAG coverages across all samples
  • note that this would be dividing coverage/abundance estimates between closely related MAGs recovered from different samples. So a dRep step may also be wanted, then making a dRep'd MAG bowtie2 db for mapping...
  • or maybe just providing a skani/ANI output for all MAGs and leaving mapping to all...