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**~~
Can you remove FASTA-Sanger? The FASTA-Sanger and SFF preprocessing steps are different. The former doesn't need to be demultiplexed.