Define API for written translation packs

[BenHenning]

The current API being proposed by #1 doesn't properly define language compatibility, and it's expected that we will leverage translation packs for this purpose (versus expecting all structures to be fully localized to all supported client languages).

[PasunuriSrinidhi]

Here is an example API for defining written translation packs:

POST /translation_packs
{
"pack_id": "my-pack",
"language": "fr",
"translations": {
"greeting": "Bonjour",
"goodbye": "Au revoir"
}
}

This API endpoint allows users to define a translation pack with a specific ID and language. The translations are provided as a key-value pair where the key is the identifier for the translation and the value is the translated text.