fix(cli): improved support for native sidecar servers in linkerd authz

[alpeb]

(Extracted from #14566)

The logic behind the linkerd authz command wasn't accounting for ports in init containers, so authorization policies pointing to those ports were not reported by the command.

Say for example you had a strict auth policy for the linkerd-admin port, allowing only access from prometheus. For emojivoto's web workload you could set that up like this:

apiVersion: policy.linkerd.io/v1beta3
kind: Server
metadata:
  annotations:
  name: admin
  namespace: emojivoto
spec:
  accessPolicy: deny
  podSelector:
    matchLabels:
      app: web-svc
  port: linkerd-admin
  proxyProtocol: HTTP/1
---
apiVersion: policy.linkerd.io/v1alpha1
kind: MeshTLSAuthentication
metadata:
  namespace: emojivoto
  name: prometheus
spec:
  identities:
  - "prometheus.linkerd-viz.serviceaccount.identity.linkerd.cluster.local"
---
apiVersion: policy.linkerd.io/v1alpha1
kind: AuthorizationPolicy
metadata:
  namespace: emojivoto
  name: web-http-sa
spec:
  targetRef:
    group: policy.linkerd.io
    kind: Server
    name: admin
  requiredAuthenticationRefs:
    - name: prometheus
      kind: MeshTLSAuthentication
      group: policy.linkerd.io

Invoking linkerd authz would return nothing, but after this change we can see the auth:

$ linkerd authz -n emojivoto deploy/web
ROUTE   SERVER  AUTHORIZATION_POLICY   SERVER_AUTHORIZATION
*       admin   web-http-sa