Expose Kuma CP config

[jakubdyszkiewicz]

Summary

There should be a way to determine current Kuma CP config.
We can start by logging the config at the CP startup, but eventually we could expose it via API Server. This way we can use some of the properties in the GUI.

There should be a way to replace secrets with *****, so we don't leak it to logs or API responses.

[jakubdyszkiewicz]

Solved by #428