[FE] Support multiple languages from translation files

[kylejwatson]

As an OpenDORA Backstage Plugin user

I would like to be able to see the UI in my own language.

Assume that:

• We eventually want to support both English and Dutch for the UI
• Benchmark summaries should be translated (Between once per month and once every 6 months)
• For this task we just want to implement a solution to switch languages, but translations don't need to be provided.
• Any translation service/manual effort can format translations into a json file with a key-value map.