a3m msa input for colabfold

[vagkaratzas]

This is an initial PR, mostly to showcase the changes needed to make an MSA input work, starting with colabfold, and then continue by building upon this. The tricky part will be to test the initial input samplesheet.csv for both options; fasta sequence files, and/or msa folder with a3m MSA files. The COLABFOLD_BATCH module conveniently works the same with both fasta and msa inputs.