Resolve "Provide a way to use Mattermost Webhooks from other Namespaces internal to a Cluster"

General MR

Summary

Create a way to allow consumers to create additional network policies using the values.yaml/overrides file.

Relevant logs/screenshots

test config below

addons:
  mattermost:
    enabled: true
    sourceType: "git"
    git:
      repo: https://repo1.dso.mil/big-bang/product/packages/mattermost.git
      path: "./chart"
      tag: null
      branch: "93-provide-a-way-to-use-mattermost-webhooks-from-other-namespaces-internal-to-a-cluster"
    values:
      networkPolicies:
        additionalPolicies:
        - name: this-is-a-mm-job-test-test
          spec:
            podSelector: {}
            policyTypes:
            - Egress
            egress:
            - to:
              - ipBlock:
                  cidr: 172.20.0.0/12
        - name: this-is-a-zwei-mm-job-test-test
          spec:
            podSelector: {}
            policyTypes:
            - Ingress
            egress:
            - to:
              - ipBlock:
                  cidr: 172.20.0.0/12

Closes #93 (closed)