Cleanup LocaleManager

[nbradbury]

This PR does two things:

• Cleanup LocaleManager by removing unused code and fixing warnings
• Convert LocaleMananger to Kotlin

These actions will make it easier to eventually do away with storing the app language in our shared preferences, enabling the system to be in charge of the language.

I left as much logic unchanged as possible, but I did need to make minor modifications to createSortedLanguageDisplayStrings to get it to work. This change can be tested two ways:

Test 1:

• My Site > Site Settings
• Tap Language
• Verify the language picker appears correctly

Test 2:

• On a pre-API 13 device, go to App Settings
• Tap the Interface Language
• Verify the language picker appears correctly

[dangermattic]

	1 Warning
⚠️	This PR is larger than 300 lines of changes. Please consider splitting it into smaller PRs for easier and faster reviews.

Generated by 🚫 Danger

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr21541-980b8d6
	Commit	980b8d6
	Direct Download	jetpack-prototype-build-pr21541-980b8d6.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr21541-980b8d6
	Commit	980b8d6
	Direct Download	wordpress-prototype-build-pr21541-980b8d6.apk

Note: Google Login is not supported on these builds.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 39.48%. Comparing base (92d71de) to head (980b8d6).
Report is 13 commits behind head on feature/per-app-language-prefs.

Additional details and impacted files

@@                        Coverage Diff                         @@
##           feature/per-app-language-prefs   #21541      +/-   ##
==================================================================
+ Coverage                           39.44%   39.48%   +0.03%     
==================================================================
  Files                                2118     2117       -1     
  Lines                               99550    99464      -86     
  Branches                            15312    15296      -16     
==================================================================
  Hits                                39269    39269              
+ Misses                              56800    56714      -86     
  Partials                             3481     3481              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[ParaskP7]

👋 @nbradbury !

I have reviewed and tested this PR as per the instructions, everything works as expected, great job Kotlinizing LocalManager! 🌟 x 🌟 ^ 🌟

PS: I especially like the fact that you add nullability annotations on the Java side before the conversion, kudos. 💯

---

I have left one questions (❓), a couple of suggestions (💡) and some minor (🔍) comments for you to consider. I am going to approve this PR anyway, since none is blocking. I am NOT going to merge this PR yet to give you some time to apply any of my suggestions. However, feel free to ignore them and merge the PR yourself.

[ParaskP7]

1. Question (❓): How come this String[] split = entryStrings.get(i).split("__"); Java related code got replace with this Kotlin related code that seems that much more involved (toRegex() + dropLastWhile { ... } + toTypedArray()). I am sure there is a good reason, I just want to understand it better... 😊
2. Minor (🔍): Consider splitting this logic into multiple lines for readability purposes:

            val split = entryStrings[i]
                .split("__".toRegex())
                .dropLastWhile { it.isEmpty() }
                .toTypedArray()

[nbradbury]

PS: I especially like the fact that you add nullability annotations on the Java side before the conversion, kudos. 💯

Thanks for noticing that! I actually attempted the conversion without addressing the nullability issues and it was a disaster :)

I've implemented most of your thoughtful suggestions but left some as-is because #21542 removes some of that code.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[ParaskP7]

I've implemented most of your thoughtful suggestions but left some as-is because #21542 removes some of that code.

Thanks for applying the suggestions @nbradbury and noted about #21542 ! 🥇

Thanks for noticing that! I actually attempted the conversion without addressing the nullability issues and it was a disaster :)

😄 I could imagine, Kotlin is as smart as it gets, but it isn't AI or God, the more we help it the better the result! 😄