Support Android's per-app language preferences

[Korb]

Checklist

• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the bug report will be dismissed otherwise.
• This issue contains only one feature request.
• I have read and understood the contribution guidelines.
• I optionally donated to support the Fossify mission.

Feature description

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.

Why do you want this feature?

Unification and following standards.

Additional information

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

[Aga-C]

We already use the system UI for language change, and we don't plan to remove it from Settings. Not every phone supports changing language from the OS-level, even on Android versions that support it (most notably Xiaomi and OnePlus devices, as stated e.g. here: osmandapp/OsmAnd#16990), and we don't want to make life harder for users of such devices.