fix: make packages registry secret optional

[daniel-palmer-gu]

Description

Fixes logic for generating registry credential secrets for packages. Since registryCredentials are required via schema, updates logic to depend on required dockerconfigjson properties.

Tests

Negative Test Case

Using default values from chart along with the following packages-values:

packages:
  podinfo:
    git:
      repo: https://github.com/stefanprodan/podinfo.git
      tag: 6.3.4
      path: charts/podinfo
    flux:
      timeout: 5m
    postRenderers: []
    dependsOn:
      - name: monitoring
        namespace: bigbang
    values:
      replicaCount: 3
  somepackage:
    git:
      repo: https://github.com/stefanprodan/podinfo.git
      tag: 6.3.4
      path: charts/podinfo
    flux:
      timeout: 5m
    postRenderers: []
    dependsOn:
      - name: monitoring
        namespace: bigbang
    values:
      replicaCount: 3

Chart successfully renders no private-registry secrets for either packages.

Positive Test Case

Using default values from chart along with the following packages-values:

packages:
  podinfo:
    git:
      repo: https://github.com/stefanprodan/podinfo.git
      tag: 6.3.4
      path: charts/podinfo
    flux:
      timeout: 5m
    postRenderers: []
    dependsOn:
      - name: monitoring
        namespace: bigbang
    values:
      replicaCount: 3
  somepackage:
    git:
      repo: https://github.com/stefanprodan/podinfo.git
      tag: 6.3.4
      path: charts/podinfo
    flux:
      timeout: 5m
    postRenderers: []
    dependsOn:
      - name: monitoring
        namespace: bigbang
    values:
      replicaCount: 3

registryCredentials:
  registry: someregistry
  username: someusername
  password: somepassword

Successfully generates the following secrets:

---
# Source: bigbang/templates/secrets/imagepullsecret.yaml
apiVersion: v1
kind: Secret
metadata:
  name: private-registry
  namespace: podinfo
  labels:
    app.kubernetes.io/name: private-registry
    app.kubernetes.io/instance: bb
    app.kubernetes.io/version: 2.10.0
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/part-of: "bigbang"
    helm.sh/chart: bigbang-2.10.0
type: kubernetes.io/dockerconfigjson
data:
  .dockerconfigjson: eyJhdXRocyI6eyJzb21lcmVnaXN0cnkiOnsidXNlcm5hbWUiOiJzb21ldXNlcm5hbWUiLCJwYXNzd29yZCI6InNvbWVwYXNzd29yZCIsImVtYWlsIjoiIiwiYXV0aCI6ImMyOXRaWFZ6WlhKdVlXMWxPbk52YldWd1lYTnpkMjl5WkE9PSJ9fX0=
---
# Source: bigbang/templates/secrets/imagepullsecret.yaml
apiVersion: v1
kind: Secret
metadata:
  name: private-registry
  namespace: somepackage
  labels:
    app.kubernetes.io/name: private-registry
    app.kubernetes.io/instance: bb
    app.kubernetes.io/version: 2.10.0
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/part-of: "bigbang"
    helm.sh/chart: bigbang-2.10.0
type: kubernetes.io/dockerconfigjson
data:
  .dockerconfigjson: eyJhdXRocyI6eyJzb21lcmVnaXN0cnkiOnsidXNlcm5hbWUiOiJzb21ldXNlcm5hbWUiLCJwYXNzd29yZCI6InNvbWVwYXNzd29yZCIsImVtYWlsIjoiIiwiYXV0aCI6ImMyOXRaWFZ6WlhKdVlXMWxPbk52YldWd1lYTnpkMjl5WkE9PSJ9fX0=

For Issue

Closes #1710