[WIP] new db download with alpha, ksize considerations

[bluegenes]

• database info is in conf/databases.csv

  • each db has alphabet, ksize, scaled associated with it
  • each db has a download link (OSF) or a local filepath (proteins aren't uploaded to OSF yet)
  • each db has some taxonomy info linked (also not on OSF yet)

• additional configuration info has been added to conf/defaults.conf and conf/system.conf. At some point we should decide which needs to contain db info - really doesn't need to be in both.

• get_databases.snakefile has some rules for downloading or linking these files.

  We can:
  a) add include: get_databases.snakefile into the main Snakefile, to use those rules
  b) use new shiny module stuff to import the rules:

          from snakemake.utils import min_version
          min_version("6.0")
          module get_databases:
              snakefile: "get_databases.snakefile"
          
          use rule * from get_databases as get_db_*
  

  b) move all of get_databases.snakefile into Snakefile.

I'd say unless you want to split other things out, maybe we should just do c for simplicity. Thoughts @taylorreiter?

Also, this is a rather complex way to do it, so the alternative is to just hardcode one database for each alpha/ksize/scaled and call it a day. 🤷🏻‍♀️