feat: improve learn ahead and timebox dialogs

[Hammadtanveer]

Purpose / Description

The "Learn ahead limit" and "Timebox time limit" dialogs use a plain text input. This PR improves them by adding stepper buttons and changing "OK" to "Save".

Fixes

• Part of Improve the "Learn ahead limit" and "Timebox time limit" dialogs #20478

Approach

Switched both preferences in preferences_reviewing.xml from NumberRangePreferenceCompat to IncrementerNumberRangePreferenceCompat which already has +/- stepper buttons and input validation built in. Added dialog_save string to 03-dialogs.xml and updated the positive button text in IncrementerNumberRangePreferenceCompat to use it.

This addresses the required changes from the issue. The optional changes (unit label and description text) are not included in this PR and can be done separately.

How Has This Been Tested?

Built with assembleDebug and tested both dialogs on emulator (API 36).

[github-actions]

Important

Maintainers: This PR contains Strings changes

1. Sync Translations before merging this PR and wait for the action to complete
2. Review and merge the auto-generated PR in order to sync all user-submitted translations
3. Sync Translations again and merge the PR so the huge automated string changes caused by merging this PR are by themselves and easy to review

[david-allison]

Can I confirm you've read our AI policy: https://github.com/ankidroid/Anki-Android/blob/main/AI_POLICY.md#new-contributors

• we already have R.string.save

[Hammadtanveer]

Yes, I have read the AI policy. I'll remove the duplicate string and use Rstring.save insted

[Hammadtanveer]

Fixed. Anything else to improve.

[david-allison]

If you request a review, it removes my previous one