WIP: split libraries from SFFs

Design is to support:

* SFFs
* fasta
* fasta and qual

Specific parameters such as barcode type will be sourced from db. Finalizing this will require touching a few other areas of the codebase and a db patch, which I'll get to as they become necessary.

**This is not tested, and not mergable yet**
There are some commonalities here with `_get_preprocess_fastq_cmd` which might suggest a finer decomposition. The name as well isn't the greatest as this method needed to handle SFF and fasta