Is your feature request related to a problem? Please describe.
A single mechanism for changing locale for all applications on a device, making life easier for both users and developers/translators.

Describe the solution you'd like
The language selector in the app is kind of a legacy UI - now that Android supports per-app language settings (System Settings → System → Languages → App languages), we should support that and eventually get rid of the in-app language selector.

Describe alternatives you've considered
Use the outdated mechanics of changing the application language through the interface of the application itself. The method is inconvenient because each application hid this setting in its own branch of the tree of its settings.

Additional context
https://support.google.com/android/answer/12395118
https://developer.android.com/guide/topics/resources/app-languages
https://android-developers.googleblog.com/2022/11/per-app-language-preferences-part-1.html