Cleanup k0sctl usage in boundless

[nwneisen]

Boundless relies on k0sctl heavily but it is still thrown together in a POC perspective. This ticket is to refactor its usage so that it is in a maintainable state. Depending on the changes made for this, it might make sense to break this into multiple tickets.

This should cover:

Remove the CLI calls to k0sctl. Use the k0s/k0sctl project’s pkg libraries instead. This will also remove the dependency on k0sctl being install on the user’s system.

Use structures from the k0s/k0sctl project’s pkg. See the thread here: This will eliminate duplicate code and allow us to use k0s capabilities fully.

This is not a complete list. There are likely other aspects of k0s that need to be cleaned up in the code.