helm chart - add value to enable or disable CRD installation

[mhanc]

What would you like to be added: Add helm value to helm chart to enable or disable CRD installation.

Why is this needed: This would allow and simplify installing multiple instances of external-dns to one cluster. Also in multi-tenant clusters, where CRD installation is not allowed, this would be an great enabler. Default value should be enabled, to not introduce any breaking changes, while allowing an override to disable the installation.

[stevehipwell]

TL;DR - Use Helm's native support for ignoring chart CRDs (CRDs in the crds dir) via the --skip-crds flag.

@mhanc that's not how Helm's support of CRDs work; you can't template a CRD in the crds folder, they're either in the chart or not. Also as a best practice Helm should be used with the --skip-crds flag as it will not mange the CRD lifecycle. Please check out #4322 for the context around the decision to include the CRD in the Helm chart.