Country and sub-division ISO code validation

[TheRBajaj]

This PR adds validation to the definitions of isoCountryCodeAlpha2 and isoSubCountryCode properties in the admin schema.
Issue: https://github.com/OvertureMaps/schema-wg/issues/117

Testing

Tested by modifying examples and creating new counterexamples accordingly and running test script.

Details

The following validation was added to isoCountryCodeAlpha2
- "minLength": 2
- "maxLength": 2
- "pattern": "^[A-Z]{2}$"

The following validation was added to isoSubCountryCode
- "minLength": 4
- "maxLength": 6
- "pattern": "^[A-Z]{2}-[A-Z0-9]{1,3}$"
- This validation comes from the ISO reference guide: https://www.iso.org/obp/ui/en/#iso:std:iso:3166:-2:ed-4:v1:en

[vcschapp]

Excellent stuff. There's an issue with the names in the counterexamples, but other than that looks good.

[vcschapp]

I found a second issue in a couple of counter-examples where they include a copy/pasted invalid defaultLanguage and the extExpectedErrors is testing the language issue, not the desired issue...

[vcschapp]

        _,--',   _._.--._____
 .--.--';_'-.', ";_      _.,-'
.'--'.  _.'    {`'-;_ .-.>.'
      '-:_      )  / `' '=.
        ) >     {_/,     /~)
snd     |/               `^ .'

[vcschapp]

🚨 This is behind the schema freeze, so we'll have to wait to merge it to dev. 🚨

[jwass]

Approved for me. But would prefer removing min/max length if they're not needed since the pattern already dictates that.

[jenningsanderson]

LGTM — Agree with @jwass, min/max length seems unnecessary if it' always 2 upper-case letters as demanded by the regex.

[TristanDiet-TomTom]

Approved, would leave the Length fields next to the pattern fields.

[vcschapp]

Doing a rebase and merge as this is a well-approved PR.

[marinrelatic]

Looks good