Generate artifacts metadata

What does this MR do?

Generates SLSA artifact metadata that is included beside each artifacts archive in the form of ${BUILD-ID}-artifacts-metadata.json:

{
 "_type": "https://in-toto.io/Statement/v0.1",
 "subject": [
  {
   "name": "script.sh",
   "digest": {
    "sha256": "f5ae5ced234922eebe6461d32228ba8ab9c3d0c0f3983a3bef707e6e1a1ab52a"
   }
  }
 ],
 "predicateType": "https://slsa.dev/provenance/v0.2",
 "predicate": {
  "buildType": "https://gitlab.com/gitlab-org/gitlab-runner/-/blob/v15.1.0/PROVENANCE.md",
  "builder": {
   "id": "https://gitlab.com/ggeorgiev_gitlab/playground/-/runners/14811533"
  },
  "invocation": {
   "configSource": {
    "uri": "https://gitlab.com/ggeorgiev_gitlab/playground",
    "digest": {
     "sha256": "f0582e2c9a16b5cc2cde90e8be8f1b50fd67c631"
    },
    "entryPoint": "whoami shell"
   },
   "environment": {
    "name": "local",
    "executor": "shell",
    "architecture": "amd64"
   },
   "parameters": {
    "CI": "",
    "CI_API_V4_URL": "",
    "CI_BUILD_BEFORE_SHA": "",
    "CI_BUILD_ID": "",
    "CI_BUILD_NAME": "",
    "CI_BUILD_REF": "",
    "CI_BUILD_REF_NAME": "",
    "CI_BUILD_REF_SLUG": "",
    "CI_BUILD_STAGE": "",
    "CI_BUILD_TOKEN": "",
    "CI_COMMIT_AUTHOR": "",
    "CI_COMMIT_BEFORE_SHA": "",
    "CI_COMMIT_BRANCH": "",
    "CI_COMMIT_DESCRIPTION": "",
    "CI_COMMIT_MESSAGE": "",
    "CI_COMMIT_REF_NAME": "",
    "CI_COMMIT_REF_PROTECTED": "",
    "CI_COMMIT_REF_SLUG": "",
    "CI_COMMIT_SHA": "",
    "CI_COMMIT_SHORT_SHA": "",
    "CI_COMMIT_TIMESTAMP": "",
    "CI_COMMIT_TITLE": "",
    "CI_CONFIG_PATH": "",
    "CI_DEBUG_TRACE_": "",
    "CI_DEFAULT_BRANCH": "",
    "CI_DEPENDENCY_PROXY_DIRECT_GROUP_IMAGE_PREFIX": "",
    "CI_DEPENDENCY_PROXY_GROUP_IMAGE_PREFIX": "",
    "CI_DEPENDENCY_PROXY_PASSWORD": "",
    "CI_DEPENDENCY_PROXY_SERVER": "",
    "CI_DEPENDENCY_PROXY_USER": "",
    "CI_JOB_ID": "",
    "CI_JOB_JWT": "",
    "CI_JOB_JWT_V1": "",
    "CI_JOB_JWT_V2": "",
    "CI_JOB_NAME": "",
    "CI_JOB_STAGE": "",
    "CI_JOB_STARTED_AT": "",
    "CI_JOB_TOKEN": "",
    "CI_JOB_URL": "",
    "CI_KUBERNETES_ACTIVE": "",
    "CI_NODE_TOTAL": "",
    "CI_PAGES_DOMAIN": "",
    "CI_PAGES_URL": "",
    "CI_PIPELINE_CREATED_AT": "",
    "CI_PIPELINE_ID": "",
    "CI_PIPELINE_IID": "",
    "CI_PIPELINE_SOURCE": "",
    "CI_PIPELINE_URL": "",
    "CI_PROJECT_CLASSIFICATION_LABEL": "",
    "CI_PROJECT_DESCRIPTION": "",
    "CI_PROJECT_ID": "",
    "CI_PROJECT_NAME": "",
    "CI_PROJECT_NAMESPACE": "",
    "CI_PROJECT_PATH": "",
    "CI_PROJECT_PATH_SLUG": "",
    "CI_PROJECT_REPOSITORY_LANGUAGES": "",
    "CI_PROJECT_ROOT_NAMESPACE": "",
    "CI_PROJECT_TITLE": "",
    "CI_PROJECT_URL": "",
    "CI_PROJECT_VISIBILITY": "",
    "CI_REGISTRY": "",
    "CI_REGISTRY_IMAGE": "",
    "CI_REGISTRY_PASSWORD": "",
    "CI_REGISTRY_USER": "",
    "CI_REPOSITORY_URL": "",
    "CI_RUNNER_DESCRIPTION": "",
    "CI_RUNNER_ID": "",
    "CI_RUNNER_TAGS": "",
    "CI_SERVER_HOST": "",
    "CI_SERVER_NAME": "",
    "CI_SERVER_PORT": "",
    "CI_SERVER_PROTOCOL": "",
    "CI_SERVER_REVISION": "",
    "CI_SERVER_URL": "",
    "CI_SERVER_VERSION": "",
    "CI_SERVER_VERSION_MAJOR": "",
    "CI_SERVER_VERSION_MINOR": "",
    "CI_SERVER_VERSION_PATCH": "",
    "FF_USE_LEGACY_KUBERNETES_EXECUTION_STRATEGY": "",
    "GITLAB_CI": "",
    "GITLAB_FEATURES": "",
    "GITLAB_USER_EMAIL": "",
    "GITLAB_USER_ID": "",
    "GITLAB_USER_LOGIN": "",
    "GITLAB_USER_NAME": "",
    "MASK_ME": ""
   }
  }
 },
 "metadata": {
  "buildStartedOn": "2022-06-17T00:47:27+03:00",
  "BuildFinishedOn": "2022-06-17T00:47:28+03:00",
  "reproducible": false,
  "completeness": {
   "parameters": true,
   "environment": true,
   "materials": false
  }
 },
 "materials": []
}

Why was this MR needed?

What's the best way to test this MR?

A simple job with artifacts will work:

job:
  script:
    - whoami
  tags:
    - local
  artifacts:
    paths:
      - script.sh

If the runners.generate_cache_metadata = true field is set in the config.toml it will generate a json file inside the artifacts zip.

What are the relevant issue numbers?

Closes #28940 (closed)