Improving logic with conditions and persistent test run ID

[yorugac]

This PR is meant as the next step to improve the idempotence problem described in #138. Specifically, it introduces simultaneous test runs with cloud output, increases robustness of the operator and introduces some API additions.

The key changes here are:

1. test run ID became part of the K6 status: this unlocks simultaneous test runs with cloud output since each K6 CR is unique now.
2. using conditions to track some key characteristics of the test run: this allows a far more fine-grained logic in the controller than before.
3. the long overdue refactoring of the logic has been hinted at but should be addressed further in the next PR(s).

Both test run ID and conditions can also be referenced as part of API.

✔️ This must be merged after PR #212 since it's built on top of that one.