add .gitlab-ci.yml

.gitlab-ci.yml

+include:
+- project: docker-images/templates
+  ref: master
+  file: docker_hub.gitlab-ci.yml
+
+build:
+  extends: .build_image_job_template
+  variables:
+    DOCKER_BUILDX_PLATFORMS: linux/amd64
+    IMAGE_BASENAME: ${IMAGE_PREFIX}/bundletool
+    IMAGE_NAME: ${IMAGE_BASENAME}:1.17.2,${IMAGE_BASENAME}:1.17,${IMAGE_BASENAME}:1,${IMAGE_BASENAME}:latest