Refactor `LocalizationMapper` to enable more checks

[freya022]

Pull Request Etiquette

• [X] I have checked the PRs for upcoming features/bug fixes.
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Changes

• [X] Internal code
• [ ] Library interface (affecting end-user code)
• [ ] Documentation
• [X] Other: Tests

Closes Issue: NaN

Description

Refactors the localization mapper since we now have the full objects, instead of the raw data.

This enables the checks on options and choices, which wasn't possible before.

Since this now adds the localized strings on the Java objects (instead of JSON), you can read those after pushing the command to Discord.