Overlapping continent/country geo-codes in AWS Route53

[averevki]

Some continent and country geo-codes in AWS Route53 overlap with each other. The more specific, country code is selected when specifying such code in the DNSPolicy load-balancing section, blocking the option to set some continents as dnsrecord geo location.

For example:
NA - North America/Namibia(Africa)
SA - South America/Saudi Arabia(Asia)
AF - Africa/Afghanistan(Asia)

List of route53 geo-codes: https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/resource-record-sets-values-geo.html#rrsets-values-geo-location

Done:

• for AWS prepend continent codes with GEO-
• update provider to set continent code in this case
• [] document this [Docs] Weighted and/or geo load balanced DNS across N clusters #253
• add some tests