Extract manifest from packaging image

Also include manifest.txt with, for example, version
info when extracting packages from the packagin image.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

scripts/pull-packages.sh

@@ -55,4 +55,4 @@ docker run --rm \
     -u $(id -u):$(id -g) \
     --entrypoint="bash" \
         ${IMAGE} \
-        -c "cp -R /artifacts/packages/* ${DIST_DIR}"
+        -c "cp --preserve=timestamps -R /artifacts/* ${DIST_DIR}"

scripts/release-packages.sh

@@ -189,7 +189,7 @@ git -C ${PACKAGE_REPO_ROOT} reset --hard ${UPSTREAM_REFERENCE}
 git -C ${PACKAGE_REPO_ROOT} clean -fdx ${REPO}
 
 for target in ${targets[@]}; do
-    sync ${target} ${PACKAGE_CACHE} ${PACKAGE_REPO_ROOT}/${REPO}
+    sync ${target} ${PACKAGE_CACHE}/packages ${PACKAGE_REPO_ROOT}/${REPO}
 done
 
 git -C ${PACKAGE_REPO_ROOT} add ${REPO}