Add support for app languages

[Rawa]

This PR adds the support for app languages. It uses the automatic way of adding languages:
https://developer.android.com/guide/topics/resources/app-languages#auto-localeconfig

If we want more finer control, we can add a custom list of languages but that would also require us to maintain that list.

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This change is 

[linear]

DROID-471 Add support for App Languages

[Pururun]

Reviewed 3 of 3 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

[albin-mullvad]

Reviewed 3 of 3 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @Rawa)

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CHANGELOG.md line 49 at r1 (raw file):

- Migrate voucher dialog to compose.
- Add "New Device" in app notification & rework notification system
- Add support for App Languages

Can this be clarified a bit? Perhaps something like:

 - Add support for setting per-app language in system settings.

Code quote:

 Add support for App Languages

[Rawa]

Reviewable status: 2 of 3 files reviewed, 1 unresolved discussion (waiting on @albin-mullvad and @Pururun)

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CHANGELOG.md line 49 at r1 (raw file):

Previously, albin-mullvad wrote…

Can this be clarified a bit? Perhaps something like:

 - Add support for setting per-app language in system settings.

Done.

[albin-mullvad]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

[albin-mullvad]

Reviewed 1 of 1 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved