Influenza: Automate group_override.json creation for Influenza A and B from assemblies

[anna-parker]

I do this here already: https://github.com/anna-parker/influenza-a-groupings, it takes at least 1-2 hours to run.

However, if not kept in sync with ingest it is likely that new sequences will not be properly grouped - ideally we should add this to the genspectrum github and run this in a github action every day.

[anna-parker]

Work on going here: https://github.com/GenSpectrum/influenza-override-groups