Add kustomize support for deploying in an existing namespace

[faarshad]

Feature Description

Current deployment of the operator via kustomization.yaml creates a new Namespace called newrelic-kubernetes-operator-system and deploys the resources in that namespace. Some organizations want to deploy the operator in an existing namespace and not create a new namespace.

Describe Alternatives

I had to use kustomize to generate raw manifests and manually remove the Namespace creation manifest which goes against the automation mindset.

Additional context

Possible solution is to remove the Namespace creation step and document that the user can create the Namespace if needed in their kustomize overlay.