Switch to using camelCase for metadata fields

[anna-parker]

resolves #2438

preview URL: https://switch-to-camelcase.loculus.org/

Summary

After a long discussion today we have decided to switch all metadata fields to camelCase to ensure consistency in fields for users.

Screenshot

PR Checklist

• Download metadata templates and results for all organisms and check this does not contain any snake_case -> confirmed for template downloads (of all organisms), confirmed download is working.
• Figure out why dummy organism is not loading on preview - wupps:
  I see the error No data found in /data/ for ingestion which is odd I thought we fixed this on LAPIS => caused by the fact that pango_lineage is a metadata type in LAPIS and pangoLineage is not, I have now fixed this

Future work

• Go through pathoplexus code and do the same thing: PR here: https://github.com/pathoplexus/pathoplexus/pull/62/files please also review
• Update example data in https://github.com/loculus-project/example_data

[theosanderson]

As I just mentioned in a message to Anna I think we should merge this as soon as it is internally consistent to avoid merge conflicts - it doesn't have to be consistent with pathoplexus and example_data until say tomorrow

[theosanderson]

Huge kudos on this work. I looked through everything and couldn't immediately find problems. I also tried the preview and didn't encounter problems. Obviously I could have missed things

[anna-parker]

Ok fingers crossed there are no issues! Sadly this will mean a lot of merge conflicts for everyone else - sorry about that!