Using topolvm image without sidecars

[nbalacha]

On Openshift, it is required to use the CSI sidecar images shipped by Openshift.
I would like to modify the operator to use the default sidecar containers available and use the topolvm image that is built without sidecars.

Proposal:
There are 3 ways to provide the images.

1. Hardcode default CSI sidecar images in the code
2. In the operator config map
3. Via operator ENV variables

Highest priority will be given to the values in the ENV, followed by the configmap. If neither of these are available, the default hardcoded values will be used.

[jmolmo]

Not only is required for Openshift. To have separate CSI images can improve operator flexibility and help to isolate problems.