WDL task samplesheet_rename_ids does not accept Illumina-style csv sample sheets

[tomkinsc]

The WDL task samplesheet_rename_ids, used by the workflow demux_deplete, fails for Illumina-style comma-delimited sample sheets (w/ header) since it expects Broad GP-style tab-delimited files.

This is the expected behavior as the task is currently written, but the task should perhaps allow Illumina-style sample sheets as illumina.py illumina_demux downstream accepts both formats.