Use status socket to store and fetch k0s runtime configuration

[trawler]

Is your feature request related to a problem? Please describe.

With the latest update to the config handling, and the introduction of the runtime config, it is possible (in certain edge cases) that the running configuration will change, whereas the static file under /run/k0s/k0s.yaml will not reflect that.

Describe the solution you would like

A further enhancement to this feature would be to completely abandon the saving of the file to a static location, and instead use the already available Status socket for fetching the running config.
We can also attach the k0s config command to this socket and add a k0s config show command to view the currently running configuration.

Describe alternatives you've considered

No response

Additional context

Depends on #1409

[twz123]

AFAICT /run/k0s/k0s.yaml is still a thing, although I'm not quite sure what problem it solves. Do you remember by chance @kke?

[twz123]

/xref #3072

[kke]

I think for overriding k0svars using values from the running instance instead of defaults, for example in k0s config status.