feature request: support unmapped BAMs as input

[znorgaard]

For some workflows, you may already have unmapped BAMs when you're ready to use splitcode and it would be helpful if you weren't required to convert them back to FASTQs.

As a specific example, PacBio HiFi data comes off instrument demultiplexed as unmapped BAMs. To do additional tag based extraction or demultiplexing with splitcode you currently need to convert to FASTQ.

[Yenaled]

Thanks -- I do think it'd be very useful as a feature (I mostly just hate writing the code to read/write BAM files which is why I haven't implemented it haha). Labeling this as an enhancement.