It is just a rough sketch, which barely works.

- Naming things: Use more appropriate names for variables.
- OO: Add `EnvironmentConfiguration`, to manage information about the
  toolkit environment.
- OO: Add `CloudJob` entity, to manage information about a cloud job,
  and to streamline passing of information.
- OO: Refactor low-level methods to `CloudCluster`.
- Capability to configure error handling based on the environment.
- Capability to conveniently acquire configuration settings from the
  environment, for obtaining the CrateDB Cluster identifier or name.
- Tests: Add `DockerSkippingContainer` and `PytestTestcontainerAdapter`.
  Both skip test execution when the Docker daemon is not running, or not
  available to the environment.
- Examples: Improve UX of `cloud_*.py` example programs.

It can be used to acquire corresponding client handles (adapter, dbapi,
sqlalchemy), in order to communicate with the database.

When not logged in using `croud login`, the "create project" operation
needs an organization identifier.