Implement extra organization privileges for superusers

[pacodelcastillolopez]

Implements two special types of superusers:

• Superusers that can create top level organizations
• Superusers that can admin any existing organization and create sub-organizations

Closes AB#1266

User changes

• None

Superuser changes

• If given the right superuser type by an admin they are able to create top level organizations or admin any organization+create any sub-organization

Admin changes

• When creating a superuser position can select three types: regular, can create top level organizations, can edit or create any organization

System admin changes

• application.yml or anet-dictionary.yml needs change
  Add the following to anet-dictionary.yml:

  fields:
    position:
      superuserType:
        label: Superuser Type

• 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

[gjvoosten]

This should be a PreviewField (check the other fields).
You should also retrieve the superuserType field in the GraphQL request.