Rename k8s driver parm from KUBE_CONFIG to KUBECONFIG

Implement this by bumping cnab-go. Also picks up other fixes.

KUBECONFIG is the de facto standard environment variable for kubectl etc.

Without this change when the user omits KUBE_CONFIG, the default kube config
will be used, which may well point to a valid cluster, though this will
effectively be the wrong cluster when the user has set $KUBECONFIG.

This is a particular issue when kind (https://kind.sigs.k8s.io/) is used as
it doesn't update the default kube config.

duffle relocate preserves tag when writing to a tagged and digested i…

…mage reference

Fixes #867

Bump image-relocation and ggcr

Thereby gain support for foreign layers and for relocating image indexes.

Bump cnab-go

To pick up cnabio/cnab-go@f8deb5c

Remove command_driver from Duffle since it moved to cnab-go (#825)

Signed-off-by: Radu M <root@radu.sh>

Merge pull request #818 from glyn/817-allow-arbitrary-image-names

Replace viper with standard JSON decoding

Add schemaVersion property to examples

Signed-off-by: Radu M <root@radu.sh>

 keep bundle and manifest in sync (#794)

* keep bundle and manifest in sync

copy all fields from manifest to bundle to ensure that bundle is not
missing any configuration that the bundle author intended.
Added unit tests to keep the two structure in sync

Co-Authored-By: Glyn Normington <gnormington@pivotal.io>