Add a Github Action to send translations to Crowdin for each merge in main (#25869)

crowdin.yml

@@ -1,5 +1,10 @@
+# This is needed for the Github Action
+project_id_env: CROWDIN_PROJECT_ID
+api_token_env: CROWDIN_PERSONAL_TOKEN
+
 skip_untranslated_strings: 1
 commit_message: '[ci skip]'
+preserve_hierarchy: true
 files:
   - source: /app/javascript/mastodon/locales/en.json
     translation: /app/javascript/mastodon/locales/%two_letters_code%.json