Add CI for Tor Browser

.gitlab-ci.yml

 stages:
   - lint
+  - update-translations
 
 include:
   - local: '.gitlab/ci/lint.yml'
+  - local: '.gitlab/ci/update-translations.yml'

.gitlab/ci/update-translations.yml

+.update-translation-base:
+  stage: update-translations
+  rules:
+    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
+      changes:
+        - "**/*.ftl"
+        - "**/*.properties"
+        - "**/*.dtd"
+    - if: $FORCE_UPDATE_TRANSLATIONS == "true"
+  variables:
+    TOR_BROWSER_COMBINED_FILES_JSON: "combined-translation-files.json"
+
+
+combine-en-US-translations:
+  extends: .update-translation-base
+  image: python
+  variables:
+    PIP_CACHE_DIR: "$CI_PROJECT_DIR/.cache/pip"
+    TRANSLATION_FILES: '
+      tor-browser:tor-browser.ftl
+      tor-browser:aboutDialog.dtd
+      tor-browser:aboutTBUpdate.dtd
+      tor-browser:aboutTor.dtd
+      tor-browser:torbutton.dtd
+      tor-browser:browserOnboarding.properties
+      tor-browser:cryptoSafetyPrompt.properties
+      tor-browser:onboarding.properties
+      tor-browser:onionLocation.properties
+      tor-browser:rulesets.properties
+      tor-browser:settings.properties
+      tor-browser:torbutton.properties
+      tor-browser:torConnect.properties
+      tor-browser:torlauncher.properties
+      base-browser:base-browser.ftl
+      base-browser:newIdentity.properties
+      base-browser:securityLevel.properties
+    '
+  cache:
+    paths:
+      - .cache/pip
+  # Artifact is for translation project job
+  artifacts:
+    paths:
+      - "$TOR_BROWSER_COMBINED_FILES_JSON"
+    expire_in: "60 min"
+    reports:
+      dotenv: job_id.env
+  # Don't load artifacts for this job.
+  dependencies: []
+  script:
+    # Save this CI_JOB_ID to the dotenv file to be used in the variables for the
+    # push-en-US-translations job.
+    - echo 'COMBINE_TRANSLATIONS_JOB_ID='"$CI_JOB_ID" >job_id.env
+    - pip install compare_locales
+    - python ./tools/torbrowser/l10n/combine-translation-versions.py "$CI_COMMIT_BRANCH" "$TRANSLATION_FILES" "$TOR_BROWSER_COMBINED_FILES_JSON"
+
+push-en-US-translations:
+  extends: .update-translation-base
+  needs:
+    - job: combine-en-US-translations
+  variables:
+    TOR_BROWSER_COMBINED_FILES_JSON_URL: "${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/jobs/${COMBINE_TRANSLATIONS_JOB_ID}/artifacts/${TOR_BROWSER_COMBINED_FILES_JSON}"
+  trigger:
+    strategy: depend
+    project: tor-browser-translation-bot/translation
+    branch: tor-browser-ci