Add the template to deploy extra objects

[ubajze]

Fixes: #462

This PR allows you to deploy additional Kubernetes manifests. These manifests can be defined in the extraObjects list. The following snippet shows an example:

---
nautobot:
  superUser:
    existingSecret: "my-secret"

extraObjects:
  - |
    apiVersion: external-secrets.io/v1beta1
    kind: ExternalSecret
    metadata:
      name: my-secret
      namespace: nautobot
    spec:
      data:
        - remoteRef:
            conversionStrategy: Default
            decodingStrategy: None
            key: secrets/nautobot/superuser
            metadataPolicy: None
            property: SUPERUSER_PASSWORD
          secretKey: SUPERUSER_PASSWORD
        - remoteRef:
            conversionStrategy: Default
            decodingStrategy: None
            key: secrets/nautobot/superuser
            metadataPolicy: None
            property: API_TOKEN
          secretKey: API_TOKEN
      refreshInterval: 1h
      secretStoreRef:
        kind: ClusterSecretStore
        name: vault
      target:
        creationPolicy: Owner
        deletionPolicy: Retain
        name: my-secret
        template:
          data:
            NAUTOBOT_SUPERUSER_PASSWORD: "{{ `{{ .SUPERUSER_PASSWORD | toString }}` }}"
            NAUTOBOT_SUPERUSER_API_TOKEN: "{{ `{{ .API_TOKEN | toString }}` }}"
          engineVersion: v2
          mergePolicy: Replace

[gertzakis]

Two minor things that happened to notice.
Please update the helm docs though to get the new stuff and pass the CI

[gertzakis]

Can you also add description key as we have in the other ones?

[gertzakis]

LGTM