feature(system-upgrade): Setup automated kubernetes upgrades

This patch enables kubernetes upgrades for all clusters, this might
needs some adjustments in the future to allow different clusters in
different versions.

In order to ensure updates, there is currently a copr fork of the
upstream kubernetes.

References:
https://git.shivering-isles.com/sheogorath/kubernetes-fedora

infrastructure/system-upgrades/kubernetes.yaml

+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: kubernetes-upgrade
+  namespace: system-upgrade
+type: Opaque
+stringData:
+  kubernetes-version: "1.21"
+  setup-copr.sh: |
+    #!/bin/bash
+    set -e
+    set -x
+    secrets="$(dirname "$0")"
+    systemd-run --same-dir --wait --collect --service-type=exec dnf install -y dnf-plugins-core
+    systemd-run --same-dir --wait --collect --service-type=exec dnf copr enable -y "sheogorath/kubernetes-$(cat $secrets/kubernetes-version)"
+  kubernetes-upgrade.sh: |
+    #!/bin/bash
+    set -e
+    set -x
+    secrets="$(dirname "$0")"
+    systemd-run --same-dir --wait --collect --service-type=exec dnf upgrade -y kubernetes kubernetes-kubeadm
+    kubeadm upgrade apply --yes
+  upgrade.sh: |
+    #!/bin/bash
+    set -e
+    set -x
+    secrets="$(dirname "$0")"
+    $secrets/setup-copr.sh
+    $secrets/kubernetes-upgrade.sh
+---
+apiVersion: upgrade.cattle.io/v1
+kind: Plan
+metadata:
+  name: kubernetes-upgrade
+  namespace: system-upgrade
+spec:
+  concurrency: 1
+  nodeSelector:
+    matchExpressions:
+      - key: feature.node.kubernetes.io/system-os_release.ID
+        operator: In
+        values:
+          - fedora
+      - key: feature.node.kubernetes.io/system-os_release.VERSION_ID.major
+        operator: In
+        values:
+          - "35"
+  serviceAccountName: system-upgrade
+  secrets:
+    - name: kubernetes-upgrade
+      path: /host/run/system-upgrade/secrets/kubernetes-upgrade
+  drain:
+    deleteLocalData: true
+    ignoreDaemonSets: true
+    force: false
+  version: "1.21"
+  upgrade:
+    image: docker.io/library/fedora:35
+    command: ["chroot", "/host"]
+    args: ["sh", "/run/system-upgrade/secrets/kubernetes-upgrade/upgrade.sh"]
+