Adjust token renewal duration and token duration when registering a cluster via CLI

[struegamer]

closes #404

[struegamer]

Local Testing:

./sveltosctl register cluster --namespace=development --fleet-cluster-context=admin@dev-cluster --cluster=dev-cluster --labels=deploy-cilium=true,env=homelab

cluster dev-cluster successfully registered/updated in namespace development.

❯ kubectl get sveltosclusters.lib.projectsveltos.io -n development dev-cluster -o yaml

apiVersion: lib.projectsveltos.io/v1beta1
kind: SveltosCluster
metadata:
  creationTimestamp: "2025-11-27T16:17:24Z"
  generation: 1
  labels:
    deploy-cilium: "true"
    env: homelab
    projectsveltos.io/k8s-version: v1.34.1
  name: dev-cluster
  namespace: development
  resourceVersion: "14223020"
  uid: 7c84fa41-a426-4099-8f9a-3ea94d7ea5b7
spec:
  consecutiveFailureThreshold: 3
  kubeconfigKeyName: kubeconfig
  pullMode: false
  tokenRequestRenewalOption:
    renewTokenRequestInterval: 1h0m0s
    tokenDuration: 5h0m0s
status:
  connectionFailures: 0
  connectionStatus: Healthy
  ready: true
  version: v1.34.1

No Test Issues:

?       github.com/projectsveltos/sveltosctl/api/v1beta1        [no test files]
        github.com/projectsveltos/sveltosctl/cmd/sveltosctl             coverage: 0.0% of statements
        github.com/projectsveltos/sveltosctl/internal/agent             coverage: 0.0% of statements
ok      github.com/projectsveltos/sveltosctl/internal/commands  (cached)        coverage: 0.0% of statements
ok      github.com/projectsveltos/sveltosctl/internal/commands/generate (cached)        coverage: 10.3% of statements
ok      github.com/projectsveltos/sveltosctl/internal/commands/loglevel (cached)        coverage: 53.6% of statements
ok      github.com/projectsveltos/sveltosctl/internal/commands/onboard  (cached)        coverage: 37.4% of statements
ok      github.com/projectsveltos/sveltosctl/internal/commands/show     (cached)        coverage: 56.3% of statements
ok      github.com/projectsveltos/sveltosctl/internal/utils     (cached)        coverage: 71.1% of statements