Add COA files for all countries from gov-id-finder.codeforiati.org

[markbrough]

This is the preferred PR. #499 is an alternative.

• Adds COA files for each country
• For countries that have codes on gov-id-finder.codeforiati.org, this is noted and example codes are given.
• For countries that do not have codes on gov-id-finder.codeforiati.org, users are encouraged to reach out and supply codes.

Note: this PR makes COA files even where a country folder does not already exist.

It does not make a COA file for Afghanistan, as AF-COA already exists.

[odscjames]

Me @kd-ods and @stevieflow have discussed - approving from all of us!