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.
This is for AT epic "reduce bam redundancy" (AT-651) that has the goal to remove per lane bam (save disk space) after bam merge succeeds. This command will be implemented to recreate per lane bam from the merged bam if this per lane bam is needed again for new bam merge later. When removing per lan bam, we mean to remove all_sequences.bam along with the .bai and .md5 files, but keep .flagstat and make all_sequences.bam.header in the directory. When recreating the per lane bam, we run flagstat on the temp extract read-group bam (made from merged bam) and compare this flagstat with the original all_sequences.bam.flagstat to make sure they are exactly same. Then we revert markdup tag in this bam and reheader this bam using all_sequences.bam.header created previously in order to make this bam resembling the original per lane bam as much as possible.  I will update the documentation soon.