Auth URL Variables

Currently we can set the server variables for different environments like so:

servers:
  - url: 'https://{environment}.example.com/v1'
    variables:
      environment:
        default: api
        enum:
          - api
          - sandbox.api
          - development.api
          - staging.api

Is it possible to also set variables for the authorization code urls? Normally you'd want to match these environments when authenticating. I'd imagine it would look something like this:

securitySchemes:
  OAuth2:
    type: oauth2
    flows:
      authorizationCode:
        authorizationUrl: 
          - url: 'https://{environment}.example.com/authorize'
            variables:
              environment:
                default: accounts
                enum:
                  - accounts
                  - sandbox.accounts
                  - development.accounts
                  - staging.accounts
        tokenUrl: 
          - url: 'https://{environment}.example.com/token'
            variables:
              environment:
                default: accounts
                enum:
                  - accounts
                  - sandbox.accounts
                  - development.accounts
                  - staging.accounts

Start by reviewing the existing server variables model and the OAuth2 authorizationCode flow described in the issue. Compare how authorizationUrl and tokenUrl are represented, then determine the supported schema for environment variables and define the expected behavior for the proposed syntax.