enable zrok env with Py SDK

[qrkourier]

Add a declarative function to enable the env unless already enabled that returns the enabled root context.

This is the Py SDK counterpart to the Go SDK feature: #510

[qrkourier]

First, I'll trace how existing functions leverage the generated OpenAPI client library. That'll instruct me in using the generated classes for calling the account "enable" operation in the controller API.

[michaelquigley]

I would actually recommend implementing (and getting this handled with a successful PR) in golang before doing it in Python. #510