Use AnyPolicyDefinitionInfo / AnyPolicyListInfo in UX1Config

[JimOverholt]

Pull Request summary:

1. Remove policy related models from endpoints directory - was causing circular import problem when trying to define an union.
2. Use separate file for each policy list model
3. Use AnyPolicyDefinitionInfo / AnyPolicyListInfo in UX1Config (which are containing both item id and definition - needed for migration steps)

Checklist:

• Make sure to run pre-commit before committing changes
• Make sure all checks have passed
• PR description is clear and comprehensive
• Mentioned the issue that this PR solves (if applicable)
• Make sure you test the changes

[JimOverholt]

This issue was migrated from an old repository: CiscoDevNet/catalystwan#523