Support localization

[XDelta]

Describe your request.

Allow for localization of the UI. Several could be pulled from Resonite's existing locales as many of text sections are just the same as in-game

Additional Context

No response

[XDelta]

Looking into other options. Started with normal flutter_localizations https://docs.flutter.dev/ui/internationalization but found a few pain points in using it that will slow things down and just be annoying.

When adding a new locale key:
You need to add the key in all locale files, doesn't appear to have any options for fallback to english/raw locale key.

• Missing locale keys will just cause the generation step to fail.
  Need to run flutter gen-l10n to generate the bindings from the arb files to be able to then add them into the code.

Ideally something closer to what Resonite does for locale where they can be defined in a json file and don't strictly need to exist before using them in code. Also allowing for falling back to the english locale or raw locale string instead if a given key isn't translated.