Command to recreate per lane bam from a merged bam

Refer to AT-658, this command tool is needed to recreate per lane bam from a merged bam. The steps involved are: extract read group bam, compare flagstat, revert markdup tag, reheader bam, create bam index, create bam md5, move outputs over.
If you're interested, these three lines could be rewritten as
```perl
Genome::Sys->write_file($out_bam.'.md5', $md5_content);
```