Split image and tag into different values in the helm chart

[ajchiarello]

To make it simpler to use a local image repository for the images in the helm chart, please split the image values into separate image and tag values. For example, where there is currently

controller:
  externalAttacher:
    image: registry.k8s.io/sig-storage/csi-attacher:v4.4.0

there would be

controller:
  externalAttacher:
    image: registry.k8s.io/sig-storage/csi-attacher
    tag: v4.4.0

This would allow the image to be redirected to a different repo without having to override the tag as well.