ACTIN-361: linx plot counts shouldn't include simple clusters

[kzuberihmf]

Skips simple clusters when counting expected linx plots (reportable clusters):

• loads exon counts from linx.vis_gene_exon.tsv
• loads chain counts for each cluster id from linx.vis_sv_data.tsv
• Filters the count of reportable clusters to remove single link clusters that don't touch an exon, consistent with this.

Recall if the accounting does not match we get a warning in the orange output, this should fix a couple of rare cases.