Restructured service code to allow for various implementations of LanguageTool as a backend and remove the burden of managing individual service implementations from the Configuration Manager.

Added a podman-based service implementation, which may eventually take place of the managed service. The service will start the named container if it exists and isn't running, or will create and start it if it doesn't exist. It expects a podman machine to be running already, and will fail to start if one hasn't been created by the user.

Also included username and apiKey settings for premium access.