gget alphafold: Add option to define jackhmmer save directory

[lauraluebbert]

    gget will currently create a "tmp" folder in your home directory ("~/tmp/jackhmmer/") for the Jackhmmer search. I think adding an option to change this path is a great idea for a future version. The temporary files will take up to ~2 GB (in case it is possible to free this space until I have implemented your request).

Originally posted by @lauraluebbert in #43 (comment)