Migrate to the official API

[joshuaspence]

Unifi Network 9.0 includes an official API. It is currently quite limited but we should be able to migrate to it incrementally.

[simonostendorf]

I am also interested to switch to 9.x.x, do you think this is as easy as generating new code for the version or should the code generation should be changed to the mentioned scala2go method @paultyng ?

I think the best solution would be to switch directly to https://github.com/hashicorp/terraform-plugin-codegen-openapi but this would require an openapi file for the new network api and I could find one (yet).