Add gisaid accession to the assembly

[anna-parker]

@cornelius found that Gisaid accessions were typically linked with a

• \note qualifier in the assembly e.g. /note="GISAID accession: EPI_ISL_20072779"
• We could also add it as a structured comment, for the assemblies that we submitted the description that we submitted is mapped to the structured comment

Ideally it would be added as a db_xref - but it needs to be registered for this

[anna-parker]

We are not able to update the assembly description field automatically as it is in the manifest, this would have to be done via email.

We need to test if we can automatically update the \note qualifier