kube/{kubeapi,kubeclient},ipn/store/kubestore,cmd/{containerboot,k8s-operator}: emit kube store Events (#14112)

Adds functionality to kube client to emit Events.
Updates kube store to emit Events when tailscaled state has been loaded, updated or if any errors where
encountered during those operations.
This should help in cases where an error related to state loading/updating caused the Pod to crash in a loop-
unlike logs of the originally failed container instance, Events associated with the Pod will still be
accessible even after N restarts.

Updates tailscale/tailscale#14080

Signed-off-by: Irbe Krumina <irbe@tailscale.com>

cmd/k8s-operator/deploy/chart/templates/proxy-rbac.yaml

@@ -16,6 +16,9 @@ rules:
 - apiGroups: [""]
   resources: ["secrets"]
   verbs: ["create","delete","deletecollection","get","list","patch","update","watch"]
+- apiGroups: [""]
+  resources: ["events"]
+  verbs: ["create", "patch", "get"]
 ---
 apiVersion: rbac.authorization.k8s.io/v1
 kind: RoleBinding