ENH: Allow selection of Nextclade dataset to open, not just use mpxv by default

[corneliusroemer]

It would be great if there was a selection possible which monkeypox dataset to use for the Nextclade integration.

Right now, mpxv is the only option, but for most sequences this is not the best choice.

hmpxv1 would be much better usually. So maybe this should become the default, and then allow the other two datasets as options.

The links are simple to adjust:

I'd use the following links (also removing the master. from the front, no longer necessary)

All clades:
https://clades.nextstrain.org/?dataset-name=MPXV&input-fasta=https%3A%2F%2Fmpox-lapis.genspectrum.org%2Fv1%2Fsample%2Ffasta%3ForderBy%3Drandom%26limit%3D200%26accession%3DOP642362%26downloadAsFile%3Dtrue

hMPXV-1 (should be default):
https://clades.nextstrain.org/?dataset-name=hMPXV&input-fasta=https%3A%2F%2Fmpox-lapis.genspectrum.org%2Fv1%2Fsample%2Ffasta%3ForderBy%3Drandom%26limit%3D200%26accession%3DOP642362%26downloadAsFile%3Dtrue

hMPXV-1 B.1:
https://clades.nextstrain.org/?dataset-name=hMPXV_B1&input-fasta=https%3A%2F%2Fmpox-lapis.genspectrum.org%2Fv1%2Fsample%2Ffasta%3ForderBy%3Drandom%26limit%3D200%26accession%3DOP642362%26downloadAsFile%3Dtrue

[corneliusroemer]

This is the button that should have dropdown selections