feat!(website): allow selecting fields to download in metadata and default to a shorter selection

[theosanderson]

resolves #850, resolves #851, resolves #3695

preview URL: https://select-fields.loculus.org/ebola-sudan/search?

Summary

Adds the capacity to select fields to download and defaults to a configured set of fields rather than to the full list.

The form to select these is quite nice. I haven't tried to merge it with the form that's used for selecting fields for the search fields and columns (or I did briefly but didn't succeed), but we can make an issue to do that in the future.

Breaking changes

You need to select which fields should be selected by default by adding the includeInDownloadsByDefault: true property in the values yaml. We should decide what this should be for Pathoplexus and make a PR before we merge this.

I made a PR: pathoplexus/pathoplexus#404

Testing

I added integration tests to check the right number of columns are present. To achieve this I added a fixture. I would request relatively light touch reviewing on the integration tests.

Screenshot

PR Checklist

• All necessary documentation has been adapted.
• The implemented feature is covered by appropriate, automated tests.
  I tested that the downloads looked good. There are also some unit tests and an integration test.

[fhennig]

Hey, thanks for implementing that! Quite useful.

I just have a few small remarks.

[theosanderson]

Thanks for the review!