Support for non-US counties?

[mlutfy]

hi @agh1, would you accept PRs for supporting non-US counties?

At first, I would make it as non-intrusive as possible: load counties for the default Country (and default to US), and eventually we could add an API call to load more counties, so that it can be done using the API explorer (and then maybe an interface, if there is demand for it).

I could help maintain it (ideally we would move it to Gitlab). I am working with an organization that would like to publish their list of counties for various countries.

Alternatively, I could create a new extension for all counties except for the US.

(I'm assuming that the main point of friction would be time spent on reviewing new lists, and I don't want to waste your time)