The operator image in the rook-ceph chart and the Ceph image in the
rook-ceph-cluster chart are both configured as a repository and tag
pair. The toolbox was the exception, taking a single toolbox.image
string.
Add toolbox.repository and toolbox.tag, so the toolbox image can be
configured the same way as the others. Either setting may be applied on
its own; whichever is left unset falls back to cephImage.repository or
cephImage.tag.
The new settings take precedence over toolbox.image, which continues to
apply when neither is set, so existing values files are unaffected.
Signed-off-by: Joshua Hoblitt <josh@hoblitt.com>