[Feature] Localisation capabilities

[grenzbotin]

In order to make the extension broadly accepted and used, we could introduce localisation that will support different languages.

** Feature description **

• Set browser language as language in extension automatically
• Fallback: English
• Create folder with localisation files
• Setup i18next
• Add a dropdown in settings that show all languages
• Ensure that number & date formats are shown correctly

Nice to have:

• Find people to translate into their mother tongue

Cons
The extension size will get larger due to localisation files.