This commit adds a new custom resource definition to the kubernetes
operator named `ProxyGroupPolicy`. This resource is namespace scoped
and is used as an allow list for which `ProxyGroup` resources can be
used within its namespace.
The `spec` contains two fields, `ingress` and `egress`. These should
contain the names of `ProxyGroup` resources to denote which can be
used as values in the `tailscale.com/proxy-group` annotation within
`Service` and `Ingress` resources.
The intention is for these policies to be merged within a namespace and
produce a `ValidatingAdmissionPolicy` and `ValidatingAdmissionPolicyBinding`
for both ingress and egress that prevents users from using names of
`ProxyGroup` resources in those annotations.
Closes: https://github.com/tailscale/corp/issues/36829
Signed-off-by: David Bond <davidsbond93@gmail.com>
a341eea00b