FIX: Allow invalid plural keys in MF translations

We can get translations with invalid plural keys from Crowdin
or from custom overrides. Currently, this will raise an error and the
locales won’t be outputted at all.

This patch addresses this issue by using the new `strict: false` option
of our `messageformat-wrapper` gem, allowing to generate locales even if
there are invalid plural keys present.

lib/js_locale_helper.rb

@@ -150,7 +150,7 @@ module JsLocaleHelper
           )
         end
         .compact_blank
-    compiled = MessageFormat.compile(message_formats.keys, message_formats)
+    compiled = MessageFormat.compile(message_formats.keys, message_formats, strict: false)
     transpiled = DiscourseJsProcessor.transpile(<<~JS, "", "discourse-mf")
       import Messages from '@messageformat/runtime/messages';
       #{compiled.sub("export default", "const msgData =")};