Move countries to locations table

[gjvoosten]

• Adds a new location type for countries and inserts countries from STANAG 1059 in the locations table; sets a few old ones to 'inactive'.
• Replaces people.country with a foreign key reference to locations.uuid.
• Migrates existing countries, using exact matches and some heuristics; keeping the old country names if we don't have an exact match, to give users the opportunity to correct this themselves.

Closes AB#1083

User changes

• Users can pick their nationality from the list of available countries.

Superuser changes

• None.

Admin changes

• Admins can maintain the list of countries via the locations of type Country.
• You can search for people with nationality "Unknown" to check for countries that couldn't be migrated automatically.

System admin changes

• anet.yml or anet-dictionary.yml needs change
  Add:

  fields:
    location:
      […]
      digram:
        label: Digram
        placeholder: Fill in the 2-letter code for this country
      trigram:
        label: Trigram
        placeholder: Fill in the 3-letter code for this country
      […]
  

  and remove the setting fields.person.regular.countries.
• db needs migration
• documentation has changed
• graphql schema has changed

Checklist

• Described the user behavior in PR body
• Referenced/updated all related issues
• commits follow a repo#issue: Title title format and these 7 rules
• commits have a clean history, otherwise PR may be squash-merged
• Added and/or updated unit tests
• Added and/or updated e2e tests
• Added and/or updated data migrations
• Updated documentation
• Resolved all build errors and warnings
• Opened debt issues for anything not resolved here

[midmarch]

Awesome!

[midmarch]

LGTM