refactor: add global docker build and run args

This reduces duplication and allows users to rely on global arguments to generate most labels needed.

The 'commit' command cannot have global arguments because the whitespace within the label change breaks string-based interpolation, and shell arrays cannot be exported.

tests/ci/setup.sh

@@ -135,4 +135,3 @@ case "$1" in
     exit $?
     ;;
 esac
-

tests/unit/40_app-json.bats

@@ -30,7 +30,8 @@ teardown() {
   assert_success
 
   CID=$(docker ps -a -q  -f "ancestor=dokku/${TEST_APP}" -f "label=dokku_phase_script=postdeploy")
-  IMAGE_ID=$(docker commit $CID dokku-test/${TEST_APP})
+  DOCKER_COMMIT_LABEL_ARGS=("--change" "LABEL org.label-schema.schema-version=1.0" "--change" "LABEL org.label-schema.vendor=dokku" "--change" "LABEL com.dokku.app-name=$TEST_APP")
+  IMAGE_ID=$(docker commit "${DOCKER_COMMIT_LABEL_ARGS[@]}" $CID dokku-test/${TEST_APP})
   run /bin/bash -c "docker run -ti $IMAGE_ID ls /app/postdeploy.test"
   echo "output: $output"
   echo "status: $status"