packaging: Add push_to_registry()

This function will push a specific tag to a registry, whenever the
PUSH_TO_REGISTRY environment variable is set, otherwise it's a no-op.

This will be used in the future to avoid replicating that logic in every
builder used by the kata-deploy scripts.

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

tools/packaging/kata-deploy/local-build/kata-deploy-binaries-in-docker.sh

@@ -47,8 +47,10 @@ docker build -q -t build-kata-deploy \
 docker run \
 	-v $HOME/.docker:/root/.docker \
 	-v /var/run/docker.sock:/var/run/docker.sock \
+	-v "${kata_dir}:${kata_dir}" \
 	--env CI="${CI:-}" \
-	--env USER=${USER} -v "${kata_dir}:${kata_dir}" \
+	--env USER=${USER} \
+	--env PUSH_TO_REGISTRY="${PUSH_TO_REGISTRY:-"no"}" \
 	--rm \
 	-w ${script_dir} \
 	build-kata-deploy "${kata_deploy_create}" $@