Add test code and Dockerfile(s) for redis cluster scaler

[goku321]

Signed-off-by: Deepak [email protected]

This adds test code and setup for redis cluster lists and redis cluster streams scalers.

Checklist

• Commits are signed with Developer Certificate of Origin (DCO)
• A PR is opened to update the documentation on our docs repo

[tomkerkhove]

@zroubalik This will require us to add the images to DH first, right?

[zroubalik]

@tomkerkhove yeah, though Dockerfiles introduced in this PR should be renamed, to not have suffix in order to get processed by the CI in here and produce those images.