Allow to control Kolga with values from Vault

[Hi-Fi]

Currently e.g. only possibility to control base URL and target namespace between multiple projects with Github Actions externally is to put the value in secrets, which prevents also logging out the URL of the application at the end of the step.

Of course there're some secrets that should probably stay in secrets (like Vault access credentials/keys and kubeconfigs), but those more like control values would be nice to get from Vault to allow easier changing of those.