Use AppCompatDelegate.setApplicationLocales

[alisonthemonster]

Replace the recreate-based locale switch with AppCompatDelegate.setApplicationLocales so language changes use the modern per-app language API and we can remove LocaleHelper.

[alisonthemonster]

Language preference now stops downloading/installing locale resources updateLanguage() now only calls activity?.recreate(), but this branch also removes the previous Play Core language install flow and SplitCompat hookup from application startup. That means changing to a locale that is not already present on the device/app bundle will no longer fetch resources; the activity will just recreate and likely fall back to the default language. If dynamic language switching is still a supported feature, this is a user-facing regression rather than just a temporary implementation