add support of consul namespaces to health checks

[kschoche]

[Consul-ENT only]

Changes proposed in this PR:

• connect-inject now adds a new annotation when Mutate is called "consul.hashicorp.com/consul-destination-namespace" when namespaces and mirroring are enabled.
• health checks are created in namespaces if they are supported+used
• existing unit tests are modified a bit to be able to re-use code between oss and consul-ent

How I've tested this PR:
unit tests have been added for the patch functionality as well as health checks resource.

How I expect reviewers to test this PR:
Unit tests.
Alternatively running and end to end test manually by:

1. deploying with consul-helm consul-ent, along with

global:
  imageK8S: kschoche/consul-k8s-dev
  enableConsulNamespaces: true
  name: consul
  image: hashicorp/consul-enterprise:1.9.0-ent-beta1
  tls:
    enabled: true
server:
  enterpriseLicense:
    secretName: 'ent-license'
    secretKey: 'key'
connectInject:
  healthChecks:
    enabled: true
  enabled: true
  consulNamespaces:
    mirroringK8S: true

2. Deploy a connect-injected application with k8s readiness probes into a k8s namespace

Checklist:

• Tests added
• CHANGELOG entry added (HashiCorp engineers only, community PRs should not add a changelog entry)

[lkysow]

I tested this on my cluster with mirroring and it worked 💯 👌 .

Some suggestions around the tests and also the logic of when to add the annotation needs to be tweaked I believe.

[lkysow]

Changes look good. Note that I didn't rebuild the image.

[ishustava]

Looks good! I left a couple of comments, but they shouldn't block the merge.