change demux_deplete to accept multiple biosample_map input files

[tomkinsc]

change demux_deplete so it can accept (and merge) multiple biosample_map input tsv files, so the user can provide metadata from multiple biosample submissions. This would be particularly helpful for flowcells containing samples where attribute data was submitted to NCBI BioSample under different attribute package types that could not be combined into a single submission (for example, Metagenome.environmental and Pathogen.cl)