[3] Add applied apps version to cluster state

[Xartos]

Proposed feature

To reduce the risk of forgetting or missing to run the apply migration step we should add some state to the cluster such that it knows what was last applied.

Then when you run the prepare command it could check and make sure that both the config and the cluster state has a valid version.

Proposed alternatives

Since we would like to be able to catch if any of the migration scrips were missed we should probably have this apply be done in the migration apply step and not directly in apps.

Additional context

Some thing to consider:

• How to implement? ConfigMap, labels, etc.
• How to handle when you are not on a tag?
• Should this only be checked when preparing an upgrade or also e.g. when running bin/ck8s apply?

Definition of done

• [ ] The current applied apps version is stored in the environment
• [ ] Some prepare step should validate that the cluster is using a valid version before continuing