nf-core/tbanalyzer test dataset: downsampled Mycobacterium tuberculosis reads

Minimal test data for the nf-core/tbanalyzer pipeline (--mode mtbseq). Two Mycobacterium tuberculosis Illumina paired-end samples (subsampled from ENA accessions ERR553286 and ERR551038) downsampled to ~100,000 read pairs (~11x coverage of H37Rv) with seqtk, together with the pipeline samplesheet (test_samplesheet.csv) and the MTBseq cohort file (test_cohort.tsv). Intended only for continuous-integration / smoke testing of the pipeline.