Added support for Android's per-app language setting.

[MohitMaliFtechiz]

Fixes #4222

• Introduced the per-app language feature in application.
• Added androidx.appcompat:appcompat-resources dependency.
• Setting the chosen language in AppCompatDelegate to update the selected language globally so that it is displayed in the system settings.
• Migrated the previously chosen language in AppCompatDelegate so that the previously selected language will remain active.
• Added support for pre Android 13 devices since this API is introduced in Android 13 so we have added the backward compatibility for this API.
• Since now, AppCompatDelegate is handling our locales and we don't need to handle it by ourself so we have removed the unused code from our application.
• Refactored the test cases to use this new API for handling the locales.
• Fixed: The message was showing in the previously chosen language when saving the file, and showing the downloading estimate time in the previously chosen language.
• Fixed: Some unnecessary memory leaks were reported in Android 14 and above devices due to https://github.com/square/leakcanary/issues/2559.

Below Android 13 devices

https://github.com/user-attachments/assets/4368b10b-bfe4-4aca-a178-ae37139084ef

Above Android 15 devices

https://github.com/user-attachments/assets/13e5fbef-9c54-495a-b76a-effc1c32facb

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 66.66667% with 6 lines in your changes missing coverage. Please review.

Project coverage is 57.62%. Comparing base (102162f) to head (2b007c5).

Files with missing lines	Patch %	Lines
...va/org/kiwix/kiwixmobile/core/main/KiwixWebView.kt	0.00%	5 Missing :warning:
...wix/kiwixmobile/core/settings/CorePrefsFragment.kt	75.00%	0 Missing and 1 partial :warning:

:x: Your patch check has failed because the patch coverage (66.66%) is below the target coverage (70.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #4228      +/-   ##
============================================
+ Coverage     57.49%   57.62%   +0.13%     
- Complexity     1582     1601      +19     
============================================
  Files           316      316              
  Lines         13786    13755      -31     
  Branches       1729     1728       -1     
============================================
+ Hits           7926     7927       +1     
+ Misses         4669     4650      -19     
+ Partials       1191     1178      -13     

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