Add filter option for nextclade

[ammaraziz]

Nextclade datasets are growing by the month. I propose a new cli option to limit the datasets that get notified. This can be done by filtering on the dataset name.

If you approve I can submit a pull request @Wytamma

[Wytamma]

What do you mean limit the datasets that get notified? Is this the same as #1 ie limit the number of characters returned?