Add Curacao and Sint Maarten

[jkikstra]

Add two countries that in 2010, like Aruba in 1986, separated from the Netherlands to become a constituent country inside the Kingdom of the Netherlands

For more, see https://en.wikipedia.org/wiki/Kingdom_of_the_Netherlands

This is a small PR, but points to larger questions (which could be transferred into a new Issue, i think):
(a) when to add new countries to the mapping?
(b) is there a way to ensure that there is no overlap?
(c) is there a way to ensure completeness?
(d) should we force IAM mappings to be up-to-date with the latest common R5/R9/R10 mapping?

How to review?

• check if this would need to be added somewhere else
• check if this is in line with the geojson data

[danielhuppmann]

Looks like we are writing useful error messages to ensure consistency across our projects. ;-)

[phackstock]

Looks good to me.

[danielhuppmann]

@lisahligono, would it be a lot of work to re-run the R5/R9/R10 geojsons for the Scenario Explorer map component with the updated country-mapping?

[danielhuppmann]

Looks good, thanks

[lisahligono]

@danielhuppmann no it's not a lot of work. I have a working script for this