Implement array type translations

[DRFR0ST]

Hi! I've finished working on the support for array translations. These will allow passing multiple translations and avoid using incremented key naming (eg. greeting01, greeting02, greeting03).

An example of translations:

const translations = {
  greetings: [
      {
        pl_PL: "Dzień dobry",
        en_US: "Good morning",
        de_DE: "Guten Morgen"
      },
      {
        pl_PL: "Cześć",
        en_US: "Hello",
        de_DE: "Hallo"
      },
    ]
}

 const translated = translate(translations, "en_US");

 translated.slogans[1] // => "Hello"

I've also added some unit tests but it still needs some real testing.