Convert locale files from ini to json format (#35489)

Migrate from the current INI format to JSON for translations. JSON is
widely supported, including by platforms such as Crowdin and Weblate.

crowdin.yml

@@ -4,9 +4,9 @@ base_path: "."
 base_url: "https://api.crowdin.com"
 preserve_hierarchy: true
 files:
-  - source: "/options/locale/locale_en-US.ini"
-    translation: "/options/locale/locale_%locale%.ini"
-    type: "ini"
+  - source: "/options/locale/locale_en-US.json"
+    translation: "/options/locale/locale_%locale%.json"
+    type: "json"
     skip_untranslated_strings: true
     export_only_approved: true
     update_option: "update_as_unapproved"