Use GitHub Action to check for missing translations (#1019)

* Use GitHub Action to check for missing translations

* fix: missing translations

* fix: Traditional Chinese in I18N_zh_CN

* fix: I18N_zh

.github/workflows/check-translations.yml

@@ -0,0 +1,21 @@
+name: Check Translations
+
+on: [push, pull_request]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Checkout submodules
+        run: git submodule update --init --recursive
+      - name: Set up JDK 11
+        uses: actions/setup-java@v1
+        with:
+          distribution: 'zulu'
+          java-version: '11'
+          java-package: jdk+fx
+      - name: Check style test
+        run: ./gradlew checkTranslations