Images recipes for Raspberry Pi 64b

Added recipes for RPi 3/4 in 64b mode booted via u-boot -- both for APT and ostree images.

Added gitlab-ci to integrate images into pipeline. No tests added since we have no test boards in LAVA.

Generated images tested manually.

.gitlab-ci/templates-artifacts-build.yml

@@ -108,6 +108,7 @@
 .ostree-image-build:
   stage: ostree image build
   variables:
+    branch: ${osname}/${release}/${architecture}-${board}/${type}
     repo: repo-${architecture}-${board}-${type}/
   script:
     - source a/*/meta/build-env.txt
@@ -124,6 +125,7 @@
         -t image:${image_name}
         -t message:${release}-${type}-${architecture}-${board}_${PIPELINE_VERSION}
         -t ostree:${repo}
+        -t branch:${branch}
         -t repourl:${ostree_pull_url}
         -t collection_id:${collection_id}
         $CI_PROJECT_DIR/apertis-ostree-image-${board}.yaml