CI: Add i18n verification step (#69384)

* Add i18n verification step

* Add check for extracted translations

* Run extract

* Add newline for pseudo

* Format JSON output with prettier

* Print file diff

* Actually run make drone

* Only deo git diff on locales

* Update error message

* Verify that step fails on dynamic phrases

* Verify that it passes when fixed

* Verify that dynamic phrase fails, for real this time

* Extract error messages

* Change echo

* Fix string format

* Try double escaping

* Escape for Drone substitution

* Update character escape

* Remove dynamic phrase

* Verify multiple keys

* Remove double keys

* Readd en locale because of reasons

* Undo changes

* Format lint_frontend.star

* Update error message

* Update .drone.yml

* Add quotes for echo

* Verify fail to extract

* Fix diff stat command

* Reset footer changes

scripts/drone/steps/lib.star

@@ -775,11 +775,34 @@ def lint_frontend_step():
         "commands": [
             "yarn run prettier:check",
             "yarn run lint",
-            "yarn run i18n:compile",  # TODO: right place for this?
             "yarn run typecheck",
         ],
     }
 
+def verify_i18n_step():
+    extract_error_message = "\nExtraction failed. Make sure that you have no dynamic translation phrases, such as 't(\\`preferences.theme.\\$${themeID}\\`, themeName)' and that no translation key is used twice. Search the output for '[warning]' to find the offending file."
+    uncommited_error_message = "\nTranslation extraction has not been committed. Please run 'yarn i18n:extract', commit the changes and push again."
+    return {
+        "name": "verify-i18n",
+        "image": build_image,
+        "depends_on": [
+            "yarn-install",
+        ],
+        "commands": [
+            "yarn run i18n:extract || (echo \"{}\" && false)".format(extract_error_message),
+            # Verify that translation extraction has been committed
+            '''
+            file_diff=$(git diff --dirstat public/locales)
+            if [ -n "$file_diff" ]; then
+                echo $file_diff
+                echo "{}"
+                exit 1
+            fi
+            '''.format(uncommited_error_message),
+            "yarn run i18n:compile",
+        ],
+    }
+
 def test_a11y_frontend_step(ver_mode, port = 3001):
     """Runs automated accessiblity tests against the frontend.