Rancher provisioned/managed RKE2/K3s data-dir support

[jakefhyde]

There is currently an ongoing effort to support specifying the RKE2/K3s data-dir argument, which allows a user to change it from the default of /var/lib/rancher/rke2 & /var/lib/rancher/k3s respectively, to a user provided directory. I've found the following instances of these directories hardcoded within the project:

• rancherd/pkg/probe/probe.go

  Lines 23 to 25 in 0e6e08c

  	CACert: "/var/lib/rancher/%s/server/tls/server-ca.crt",
  	ClientCert: "/var/lib/rancher/%s/server/tls/client-kube-apiserver.crt",
  	ClientKey: "/var/lib/rancher/%s/server/tls/client-kube-apiserver.key",

• rancherd/pkg/kubectl/kubectl.go

  Line 28 in 0e6e08c

  kubectl = "/var/lib/rancher/rke2/bin/kubectl"

Please review the above information, and feel free to reach out to me regarding questions. The api changes can be found within this draft PR within rancher/rancher: https://github.com/rancher/rancher/pull/45326/files#diff-6f7b3ace8ec7df668da64642416a1171322908df345c8e339d314bac3ed08af6R57.