Implement seq2seq model for gene clusters

[jgoodson]

https://github.com/FIRE-CB/TraGeC/blob/b7fde9ea3c9b38154533289aa3b68de45613eaf3/tragec/tasks/task_seq2seqclass.py#L69-L69

Our end goal is to do gene-level prediction of gene cluster membership. We do not currently have this feature. We should implement a sequence to sequence classification model to enable us to train and predict at an individual gene level on whole genomes or contigs.