Add validation for ISO 3166-1 Country codes

[aviiciii]

Add country code validation for

• Alpha-2 code
• Alpha-3 code
• Numeric

link:

• https://www.iso.org/iso-3166-country-codes.html
• https://www.iso.org/obp/ui/#search

[aviiciii]

Any maintainers? I am interesting in contributing this. shall i go ahead?

[yozachar]

Sure, PRs are welcome. You might want to take tips from #276 on PR review.

[aviiciii]

ok cool, will work on this