Allow creation of registry service account with values

Feature Request

Why

We are attempting to apply IAM roles to our service accounts in Kubernetes. Right now we have to manually, or otherwise, create a service account after deploying BigBang.

The current Harbor chart allows you to inject the name of the Service Account, but does not create the ServiceAccount object.

Proposed Solution

Create a template to allow the user to create a Service Account, with customizable annotations and labels.

The template would look something like Velero implements here.