Add new required field to ClusterExtension spec for users to reference a ServiceAccount

[everettraven]

In order to begin using a ServiceAccount to install and manage content, a user needs to be able to specify a ServiceAccount for operator-controller to use when creating a ClusterExtension. Since OLMv1 will not have any permissions for installing and managing permissions by default this will need to be a required, immutable field.

An example of what a ClusterExtension resource could look like with this additional field:

apiVersion: olm.operatorframework.io/v1alpha1
kind: ClusterExtension
metadata:
  name: clusterextension-sample
spec:
  installNamespace: default
  packageName: argocd-operator
  version: 0.6.0
  serviceAccount:
    name: argocd-installer

Acceptance Criteria:

• A new required, immutable field in the ClusterExtension spec for specifying a ServiceAccount that should be used to install and manage content
• Updates to unit and e2e tests as necessary

[makon57]

/assign

[everettraven]

This is done as of #1011