packaging: Add and export CC_BUILDER_REGISTRY

CC_BUILD_REGISTRY, which points to quay.io/kata-containers/cc-builder,
will be used for storing the builder images used to build the artefacts
via the kata-deploy scripts.

The plan is to tag, whenever it's possible and makes sense, images like:
* ${CC_BUILDER_REGISTRY}:kernel-${sha}
* ${CC_BUILDER_REGISTRY}:qemu-${sha}
* ${CC_BUILDER_REGISTRY}:ovmf-${sha}
* ${CC_BUILDER_REGISTRY}:shim-v2-${go-toolchain}-{rust-toolchain}-${sha}
* ${CC_BUILDER_REGISTRY}:td-shim-${toolchain}-${sha}
* ${CC_BUILDER_REGISTRY}:virtiofsd-${toolchain}-${sha}

Where ${sha} is the sha of the last commit modifying the Dockerfile used
by the builder.

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

tools/packaging/scripts/lib.sh

@@ -8,6 +8,7 @@
 export GOPATH=${GOPATH:-${HOME}/go}
 export tests_repo="${tests_repo:-github.com/kata-containers/tests}"
 export tests_repo_dir="$GOPATH/src/$tests_repo"
+export CC_BUILDER_REGISTRY="quay.io/kata-containers/cc-builders"
 
 this_script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"