The TemplateConfig resource is only read by the controller's k8s client
when the devmode CLI flag is set.

The TemplateConfig spec has fields for the various templates for VCL
generation: ingress, self-sharding, ACL etc. The value type for all
of those fields is string, and each field is optional.

When a TemplateConfig specifies a value for a template type, the
controller attempts to parse it as a text/template.Template, using
the same function map defined for the template type. If the parse
fails, then the error is logged and an Event type Warning with the
error message is generated, and the field is ignored.

If the parse succeeds, then the template is replaced for all further
VCL generation by the controller.

When a TemplateConfig is deleted, then for each template type that it
specifies, the template is reverted to the controller's standard value.

In this first iteration:

- only the ACL template is updated, will add the other types.

- only kubectl deployments are supported, will add support in the
helm chart for the viking controller.

- we have an e2e test, but it is not yet added to the e2e script that
runs all of them, or to the gitlab CI script, since these have to
support helm deployments.