Add label with the current app language to the App Settings screen

[ovitrif]

Fixes #16483

Shows a label with the current app language in App Settings, under "Interface Language".

To test:

1. Open the WordPress or Jetpack app of this PR (QR-code or local build)
2. Tap on the profile icon to open the Me page
3. Tap App Settings
4. Expect a label with the current language to show under "Interface Language" (in the first list item)
   Optionally:
   • Tap Interface Language and select choose another language
   • Expect the label to update and show the new language that you've selected.

Preview:

English (Day Mode)	Dutch (Night Mode)

Regression Notes

1. Potential unintended areas of impact
   Language Picker.

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   Tested manually.

3. What automated tests I added (or what prevented me from doing so)
   Updated LocalePickerViewModelTest unit tests.

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[wpmobilebot]

You can test the Jetpack changes on this Pull Request by downloading an installable build (jetpack-installable-build-pr17004-a5985da.apk), or scanning this QR code:

[wpmobilebot]

You can test the WordPress changes on this Pull Request by downloading an installable build (wordpress-installable-build-pr17004-a5985da.apk), or scanning this QR code:

[antonis]

Great work @ovitrif 👍
I tested the CI build on a Pixel 5 (Android 12) and everything worked as described. The code changes also LGTM 🎉
Thank you for wrangling this 🙇